myasthenia gravis and or thymus gland trouble

Myasthenia gravis, as I have discovered seems to can be related to various thymus gland problems.

In the last 9+ months I have had a problem with a constant pressure type headache, but with a feeling of tension and weakness in the muscles that raise my eyebrows (though I have never lost any range of motion in movement), and from time to time I get ocular motor trouble such as positional nystagmus, or nystagmus caused by cutting my eyes sharply in any direction (the bounce-back effect).    

The cranial symptoms (especially the forehead tension/weakness) are virtually constant.   I have also had intermittant problems with taking a deep enough breath...It feels like the area in my upper center chest, almost to my throat, gets tight and constricted and I don't feel as though I can get a refreshing or deep enough breath.  It feels really like the muscle that controls my breathing is constricted or weak.  I have also had trouble not really with swallowing but with gagging on food (I subconsciously inhale as I'm swallowing something)  and this seems to coincide with my breathing troubles.

Exercise especially lifting weights aggrivates the tension in my forehead, so I've quit lifting weights alltogether.

Does it sound like myasthenia gravis? Can MG cause headaches? I have never been able to connect this to my upper chest/breathing problems til I read about the thymus and its relation to MG.How can this be ruled out? I've had a chest xray, MRI brain, and a mound of bloodwork. Neuro refused to order LP even though I insisted. What can i do doc?  I am 31/male/w. thanks