Levoxyl and muscle weakness

I've been taking levoxyl for 8 years now with mostly good success. My endo doctor recently upped my dose due to lab results (I think the test results were bad). Now I feel horrible. Headache, dizzy/lightheaded, blood pressure increased, tightness in throat, and muscle cramping. I've been to many specialists concerning the dizziness - everyone says I'm OK; cardiologist, ENT, and neurologist. The symptoms started a few weeks after the dose increase, and have worsened in the last week or two (about 2.5 months out).

I have been on thyroxine for about 3 years.I have been allergic to some brands, but lately every brand I try I am allergic to it.My symptoms are extreme nausea and muscle weakness ,off to g p on Monday to try to get him to belive meCAN ANYONE HELP.

For a year I had all the symptoms of hyperthyroidism, rapid heart beat, muscle weakness, no sleep, bulging eyes, weight loss, etc., but the drug Evista masked the thyroid lab tests. When I ceased taking Evista, a subsequent lab test showed extreme hyperthyroidism. No doctor treating me knew of the connection. After treatment with nuclear medicine, I became hypothyroid and required Levoxyl. Dosage is monitored and has remained at 75 mcg for two years. I am "cured" because my thyoid is now normal, and I have absolutely no side effects from the Levoxyl. I am a 70-year-old woman who hates to take pills, but this is mandatory. I had lost 15 pounds and in two years have gained 5.