Really Need Help!

So, I have IBS and I don’t know if this has anything to do with it but anyway..

Sometimes, I’ll get a burning feeling in my vagina (I don’t know where the burning is because it literally feels like my whole vagina is burning). It’ll go away, then it’ll come back. When the burning is there, it hurts to pee but when I’m not experiencing burning, the burning when I pee is not there. What I’ve noticed, is that my pee can be really yellow at times but not all of the time. Like, I’m almost finished my period and this month, the burning was there the first day of my period and my urine was yellow. Another thing, is that after I pee, I’ll stand up and if I push (as if I’m passing stool) there’s like a pressure and pain in my lower stomach. I always have lower stomach pain that goes into my lower back. It can happen at anytime but I’ve noticed it happens a lot after I finish my period. I suffer with severe constipation so I got some stuff from a pharmacy that’s helped me a lot but I think all of the problems I’m having are still there. I feel like I’m not completely ‘emptied out’ if that makes sense? Like, I’ve gone a couple weeks without passing stool it’s very severe. Does anyone know what this could be?