You may not like what I have to say ... but, you know me ... I'll say it anyway.
Your rotator cuff is essential to the movement of your arm and even your hand ... as you are finding out. If you continue to use it damaged, you will continue to damage it even more. As one very wise doctor told me many years ago ... pain is our body's way of saying "Easy does it ... something here is wrong." If that part of your body "freezes" or refuses to move, it is telling you, "If you make me move, I will do some permanent damage." What surgery could be done now, would probably be less than what will have to be done in the future, if you continue to damage it. But ...
on the other hand ... the procedures could improve as years pass.
So, you have to consider both sides there.
One of those 6 of one and 1/2 dozen of the other situations.
It depends on how often it messes up and how bad.
Keep this in mind: If the pain is so bad it's keeping you out of classes, it will keep you out of work, also. That line of work does not have a "regular" pay check and people (your customers) are not that good at understanding that you can not fix their hair, when and every time they need you to do so ... that is a part of a female that is her "crowning glory" and must be done for her to go anywhere and be seen.
You might think about changing your career ambitions.
Now to get down to the bad part ...
When and how did you injure it?
Did the doctor do a dye-enhanced x-ray? Did you see the x-rays? If you saw them and saw what looked like white streamers leaving your rotator cuff ... that is where the tear/tears are.
If it is just a little bit of it ... good chance it will heal on it's own ... no harm in giving it a chance to, anyway.
But, if there are long streamers and more than one or two ... there is some major damage and surgery is needed.
Possible surgery?
First, I would find a doctor that can give me a % rate on the recover with the surgery ... if he can not give you at least 75% chance of it being useful after surgery ... find a doctor who can.
When explaining the procedure, if he says he will have to lay your shoulder open front to back ... find a doctor that can do it orthoscopically (sp).
My local doctor told me what yours told you and was going to open me up front to back. I told him "Thanks, but no thanks."
I went to Duke and Dr. Kevin Spears (he is in private practice in Raleigh or Durham, NC, now) did 5 different procedures othoscopically and all in one surgery. I still have some slight pain every once in a while ... but never enough to stop me from doing what I want to do, usually. I have full use of my arm and hand, most of the time. No one can make it perfect again, man is not as good at those things as God is.
I took cosmetology, too, and graduated a few years before I tore my cuff due to a grand mal seizure. Even with it repaired, I know cosmetology would put to much of a strain on it. It will never be as strong as it was. I found out photography was actually my niche in life ... that, and chinchillas.
You are young enough to give it a little time, see what happens ... if that doesn't work ... go from there.
If you have to have the surgery, if you need it, your age is to your advantage there, too.
At your age, you also have the option to change what you want to do in life.
I empathize with your pain ... their will be times you won't even be able to lift your hand, let alone pick-up a salt shaker ... before it gets that bad ... find a competent doctor.
Nothing wrong with asking for a second opinion
except, that the doctor and anyone in his/her group can not do the surgery on your shoulder ... because they gave you the second opinion.
What you might think about doing is ... call your GP ... do NOT ask him which doctor YOU should go to ... he can't tell you that ... BUT ... you can ask him, "If you had this problem, which doctor would you have fix it for you?" That way, he is not telling you who to go, but telling you where
he/she would go, under the same circumstances ... which is even better.
The medical rules are strange, but there for a reason.
If the doctor giving you the second opinion could do the surgery, it might influence his decision. (Making him more money and maybe surgery you don't even need.)
If your doctor can not tell you where to go ... he is not downing any other doctor, and he can not get any kick back.
Both rules are there to protect you, but they often get in the way of the proper and the best care.
Keep us posted!
Jo Ann