Young people in your age group do get type II diabetes today.

It would depend on your weight, and food intake previously.
(lots of sugar for example, or heredity)

Obviously the CC doesn't keep up:
http://neurotalk.psychcentral.com/thread158275.html

They are not looking for prediabetic conditions in your age group, obviously, when other places do have young people developing type II.

At your age, I'd look at vaccine history. Do you get vaccines?
did you get them recently?

Do you take acid blocking drugs? Have you been exposed to toxins? In chem lab?

If you take fish oil, then you need magnesium. Magnesium is a cofactor in utilizing fats properly. You can buy topical forms and rub it on, which might be easiest for you.
Some CVS pharmacies still have the Epsom lotion (they are discontinuing it I guess because of slow customer response). My store still has it, for example. Another topical is called Epsom-It...and is still available online. Or you can take magnesium supplements-- any type except for OXIDE ..which is not absorbed and stays in the bowel.

Magnesium helps to relax muscles etc, when they are tight or stiff.

It is unusual for a young male to have autoimmune disease, but it is possible.

If you are working out, lifting weights, or some such, I'd give that up for a while. See if things improve. If you carry a heavy back pack around all day, or sit for long periods at a computer, shoulder issues can happen with poor posture. Small strains can happen when you overdo things. With spotty food intake or other "burning the candle at both ends" young people often get into difficulties which can be reversed with easy interventions.

If you went overseas? Did you get vaccines for that? Did you eat strange indigenous foods? Some parasites cause hard to diagnose symptoms.