Confusing symptoms

I've had my Mirena for 3 months now. I'm trying it to reduce extremely heavy periods as a last ditch solution before a hysterectomy. I'm getting all the usual symptoms that I'm handling fine, such as the bleeding for weeks (which is slowly decreasing), sore breasts, the occasional light cramping. For the last 2 months I have been feeling like crap though. I'm tired, I keep getting sore throats (and my throat stays red even when it's not sore), I get chills and flushes, and I'm short of breath. I've been to the docs twice now. No bacterial infection in throat, blood pressure fine, heart fine, all blood work is fine. I'm thinking maybe it's my Mirena, but the sore throat has me stumped. Anybody else getting a sore throat coming and going?