I have all symptoms of pid except discharge. over years myself & partners have been tested for sti's and always clear. i have 2 iud fitted before could they have caused a none sti leading to pid? is discharge essential? what else could this be?

Not all PID is due to STDs, and infection is a possible side effect of IUDs, or uterine inflammation if an IUD becomes embedded in the uterus wall. But there are plenty of other causes of pelvic area pain other than PID -- various gyn and gastrointestinal conditions. Your doctor(s) -- gynecology, gastroenterology, and/or genitourinary medicine (GUM) should be able to sort this out. Good luck.