I'm not familiar with the Supreme Science Nuggets ... could you provide a URL to it's site, please?
Mastitis can be very dangerous, I would be a bit leery of allowing her to breed again. If it was something with her that caused it, it could reoccur. If it was caused from damage from the kits, I would not be as concerned about it happening again. It could have been caused by two kits fighting over the same tit, I have seen this happen and the mom lost the use of the tits on that side because of it. (Chin moms have two completely separate sets of mammary glands.) She did have a few litters after that, without issues. Had I not know for sure it was due to the kits, I would not have allowed her to breed again.
Breedback can also be dangerous ... if the kits are still in the cage with her (especially if they are still trying to nurse), they need to be in their own cages. From the time the kits started nursing her again, her "resources" were being divided between the litter she is carrying (if she is pregnant) and the litter she is nursing.
WARNING: If there are any male kits in the same cage as momma, they can get her pregnant. A male kit has the ability to impregnate a female at the tender age of 10 weeks old. Chinchillas will breed within the family. A female kit has the ability to become pregnant as early as 3 1/2 months old, but it is doubtful she could carry them to term and she could/probably would die trying. The kits born on April 6th are now 12 weeks old. Kits should be weened at 6 weeks, no later than 7 weeks of age, unless there are special circumstances ... like they were born premature and are still very small.
She could be pregnant, only time will tell. If not by her hubby, who is now in chinnie heaven, maybe by a male kit of her own, if it is still housed in the same cage with her.
Another warning: Spock and Ffynn need to be housed in two different cages. Males have been known to fight to the death for the privilege of breeding a female that is in season ... even if they can not get to the female, they can/will still fight over her.
Pippi, the female can stay in the same cage with her mom, at least until the next litter is born, if there is one on the way.
chinchi (the dad) ... was neutered and unfortunately had complications and died three weeks ago after a surgery to remove a puss capsule
This is the reason I always am against neutering, unless it is a case of life and death.
Cuttlebones (find them in the bird section of the pet store) are a better source of calcium or even calcium tablets are OK. Keep in mind that for calcium to be properly delivered to the system and used, it needs to be in an acid environment ... Tums are antacids.
Small amounts of fresh veggies are OK, but only in small amounts and using those that do not cause gas, is very important to keep in mind. For humans gas is very uncomfortable ... for chinchillas, it can be deadly.
Hope this helps with some of your questions.
Jo Ann