Welcome Sam!

I don't know what tests you have had (if any). My neuro dx'd MG...and then did the tests to confirm. At the time my symptoms were irritating (to me), but very mild - like yours.

A CT scan, lung function tests, EMG, MRI brain and spine...frankly, I thought it was overkill for my complaint. Now that I know a bit more, I understand the tests (in my case they needed to rule out MS, vasculitis, etc.).

I would encourage you to read about MG and talk to folks here and to your doc. There are many 'degrees' of MG - it differs from one person to another...or from one day (or sometimes by the hour) to another for the same person. For me, sometimes I can string two 'good' days together before I'm exhausted!

Above all, listen to your body. If you're tired - rest. If your legs feel like jello - don't panic....rest. Then tell your neuro!

Good luck with your half marathon - - just don't push too hard until you have a good idea about what's going on.

Sue