Have mirena for 3 years. last few months, been spotting for 2-3 weeks at a time more often than not. mostly brown and sticky, no smell. most times after sex spotting starts as red, then goes light brown and continues for 1-2 weeks. is this normal?

Need evaluation : The amount of hormone in Mirena does decrease slowly over 5 years & that may be the problem, but there can be other causes such as cervical or vaginal infections which should be ruled out. I recommend to call the doctor who placed the Mirena for advice on what to do but likely will want to examine you & possibly do some lab work.