I have had mirena (levonorgestrel) for 3 months and am having worse pain with endometriosis. i can barely feel the tip of the string. how do i know if pain is ok?

Pain is not ok: It would be wise to consult your Gyn, to have a pelvic sonogram, to reevaluate your diagnosis of "endometriosis", ..and confirm that your Mirena (levonorgestrel) is in proper place in your uterus. Since the cause of pelvic pain and the alleviation of pelvic pain are often quite challenging, you may have to review/rediscuss your options for medical management and / or surgical treatments periodically.