Pain shoots up my back with constipation, is it Endometriosis?

I went to the doctor about 3/4 months ago, complaining about a pain that sort of shoots up my bum whenever I sit down, and constipation that would come in waves, and pain around my lower back. he prescribed me with laxido sachets, twice a day. I went back a month later, and I was going to the toilet more regularly but the pain was still there. He told me too carrying on taking the sachets. When i returned for the 3rd time, he said I was still all built up and too take the sachets, still twice a day, and also a tablet (unsure of the name) which after reading the paper insert in the box, is often prescribed for stomach ulcers. I am going to the toilet a lot, and my stools are soft, but I still have the pain when I sit, and sometimes at other occasions. This is really starting to concern me now! I have realized that it is worse the closer I am too my period, and my periods seem a little heavier than before all these problems started, and trying to pass stools when I’m on my period is agony! This is usually always accompanied with bloating and a swollen tummy, and having sex is always uncomfortable/painful! is it possible that Endometriosis is a possible diagnosis?