Running & Thyroid Problems?

Hey guys,
I was not sure where to put this but I figure this might be as good a place as any. So anyway, I am trying to take up running but I need advice. I started the C25K program in August but had to quit mainly because of thyroid problems. I actually don't have a thyroid because I was born without one and have some other related issues that I have dealt with my entire life. My TSH levels were almost 12 when they were tested in late October, which makes sense because I was sick for several months. I am not overweight at all (I'm 5.5 and weigh 119) and was actually quite active until this year.

I have taken Taekwondo/Karate for almost ten years (training 2 hours/3 times per week). I did stop taking Martial Arts this year because I was busy with other stuff and I didn't feel good. I walk about 2 miles every other day so it's not like I have never participated in any kind of exercise in my life. Anyway, I was wondering if taking up running is soooo HARD for everyone in the beginning or if it may be slightly harder for me because of my thyroid issues? I don't want to blame that but I have never had such a hard time with anything in my life. And my levels were way off-probably more than they have ever been in my life! My doctor upped my medication to 150mcg and I am supposed to have bloodwork done in Feb. Should I wait until my levels come down or am I safe to try C25K again? I am feeling much better since I quit but I am not sure that I am up to the challenge.

Sorry if this was slightly confusing. Any insight you guys could give me would be most appreciated!