Endometriosis

Lydia
I had endometriosis removed on 26/4/16 which was 3 weeks ago. I have been ttc for 2.5 years, had one <a href="https://glowing.com/glow-fertility-program">IUI</a> and two cycle of <a href="https://glowing.com/glow-fertility-program">IVF</a>.  No doctor had advised me to check about endo. I ended up getting a laparoscopy done because one day I was on my period and was painful. I realized that first day of my period had always been suffering that I couldn't concentrate working or had to come home early and had rests. I also realized that my period was heavy and lots of clots. I was reading on the Internet and came across about endo and saw a gynecologist and he suggested me to get a laparoscopy done, h&c hysteroscopy and dye study. Previous to this, all tests done for <a href="https://glowing.com/glow-fertility-program">iui</a> and ivfs (tube dye tests, normal regular cycle, etc) showed that everything was all good. So they suspected the delay in my pregnancy due to my husband's sperm count/quality. 
Now I have been experiencing a quite severe pain on my lower back on my left side. It felt like when I hold my pee for a little while. I was also constipated due to different diet that I am getting in overseas (Croatia). Two days ago I was admitted to the hospital because of the back pain and fever and heartburn. They did urine, blood and X-ray both on abdomen and back - all results came out good. They sent me to a gyneacologist and I had an ultrasound scan and another test also came out good. Nothing is related to my endometriosis operation.  I was only given some painkillers. Since then I have been taking a pain killer once a day because the pain in my lower left back still come back not knowing why and have never happened before.
My period has always been regular. I  am due for my period tomorrow and this is first period after laparoscopy. 
any body experiencing anything similar after endometriosis has been removed?