Synthroid dosage increase = itchiness?

My Synthroid dosage was increased from 50mcg to 75mcg on 5/15. On 5/22 I started experiencing itching, mostly on my arms. I went to urgent care that Saturday (was out of town), was given script for 40mg prednisone and topical Benadryl cream. I had thought I had gotten into some poison when I was trimming some brush a few days prior.

Finished up the prednisone Thursday morning. Was still itchy throughout the week, but it got worse again Thursday afternoon, and my heart also started racing. Today my heart has calmed down, but I am still itchy, primarily my arms and my face.

I have read that starting Synthroid can cause itching, but what about increasing the dosage? I have an appointment with my gp on Monday to address the itchiness. Any advice?

Still itchy two weeks later. Primarly my face/head and arms. It comes and goes. I emailed my endocrinologist but have not gotten a reply. It's a hot prickly itch that requires scratching for relief.

I have found some relief from loratadine, so I take it when things get rough. Plus my allergies have been acting up a bit as well.