Gained 50+ lbs severe pmdd & vulvar dermatitis after tubal ligation. Is there a such thing as "post tubal ligation syndrome? " treatment options?

Yes and no. The nih opines that tubal sterilization is not associated with an increased risk of menstrual dysfunction, dysmenorrhea, or increased premenstrual distress in women who undergo the procedure after age 30 years. There may be some increased risk for younger women, although they do not appear to undergo significant hormonal changes. I believe that more info is neded on women of your age.
50 +lbs can be a lot. After post tubal ligation there may be some swelling due to increased fluids due to IV drip or just drinking lots of water right before procedure. When you get home try walking a few steps if ok with your doctor.