Definitely seek medical advice. Drinking cranberry juice helps UTI's and it doesnt taste bad either. But being itchy and stinging sounds like thrush. Make sure you drink lots if you are breastfeeding too, as that may be contributing to the constipation as well as any painkillers you may be on. I had awful constipation after DS cos i was bfing and couldnt keep up my fluids (i got dehydrated during the birth and couldnt back on top of it). I hope you feel better soon.