Welcome to hcm
The symptoms you have explained possiblly due to side effects of pills.
As explained by your gynecologist drinking water does helps
As your echoscopy is normal. Which I presume is done by experienced specialist. The worry recurrent endometriosis
However after stage iv endometriosis the chances of recurrent disease is there.
You symptoms could possibly be due to recurrent disease. ..
My advice is to go for mri
/ ct scan
examination if symptoms persists after consulting you gynecologist.