Background: early 20's, no personal/family history of health problems or allergies. I'm not on any medications (including birth control)

Symptoms and when they began:

1. Constant urge to pee (~1 year ago)

2. Huge weight gain (20 lbs) with no apparent cause (~6 months ago)

3. Lethargy, no energy, no motivation, tired no matter how much sleep I get (a year ago)

4. Terrible dandruff and itchy scalp (tried all of the shampoos, etc.) (around 2 years ago)

5. Thinning hair (falls out a lot in shower) (2 years ago)

6. Prolonged stomach cramps for no reason (6 months)

7. Indigestion (4 months)

8. Burning feeling in stomach (not heartburn) (1 month)

9. Sharp stomach pains randomly, or when trying to pee (5 months)

10. Back pains, achiness, sore muscles (2 years)

Just recently started having weird, irregular periods.

What the hell is wrong with me? I thought the peeing thing would be a UTI, but got tested and it wasn't it. Some have suggested I may have a thyroid issue? Mostly concerned about the weight gain and peeing. Tired of losing sleep because I have to pee so much. I am petite, and fairly active with a high metabolism and I have never had weight issues in my life.

Any ideas?