hello there.
My name is Dr. Anil Jain.
as per your complains, I would suggest you to wait for a few more days for your periods, because it is seen that normally also one may miss periods by a few days.
stress, hormonal issues etc can also cause such problems. so take your
thyroid medication on time, avoid stressing out.
and for your pain you could consult a gynaecologist because establishing a cause without examining is not possible.
if your periods don't come in a few days, meet your gynaecologist in person and get examined and discuss your issue.
as of now I'd just say you wait for few days as you are not even sexually active.
hope this helps.
regards