Annie, thank you for the info and mostly for thinking of me.

You are right, I may actually have low blood pressure or maybe it is not related. I will describe some of what I am feeling.

The symptoms that I am having are these (this comes and goes but seems to happen regularly every few weeks and can last for 1 to 4 days):
-Rapid heart rate, seems to be about 100 to 120 beats per minute while at rest.
-Tense muscles, mostly my shoulders and neck which I am consciously relaxing every few minutes
-Feel stressed and nervous
-Sometimes feel out of breath, but not always.
-Sometimes shaky

My guesses as for causes:
-Too much Mestinon
-Not enough Mestinon
-Dehydration (I drink a lot but I almost always feel thirsty or dehydrated)
-Stress (definitely part of the cause)

I have noticed that I get this rapid heartbeat often if I have a stressful moment either
1) during the 30-40 minutes following taking Mestinon when I first start to feel the positive effects or
2) when I am starting to feel weak because I am due to take Mestinon again.
After my heart starts beating fast it doesn't go away for at least a few hours and sometimes days.

I have completely stopped drinking caffeine and that doesn't seem to make a difference. I am not eating or drinking anything out of the ordinary just to make sure it is not some new food.

When I go to bed, it often stops, but not always. What seems to stop it is not the laying down but the relaxing. I use a type of mental relaxation technique to fall asleep (couldn't fall asleep in the past and had to teach myself to fall asleep). I have tried something similar during the days when this happens and sometimes it helps but other times I am unable to mentally relax. I think I have a stress problem and that the Mestinon (or the MG) is making it worse somehow, or maybe my stress caused the MG in the first place and I am getting worse. My neuro won't talk about it, says it is not MG or Mestinon related.

Similar things were happening to me before I decreased my Mestinon dose from 60 mg to 30 mg. I have tried decreasing my dose from 30mg to 15 mg but then I feel weak (but not terribly so) so I haven't stayed at that dosage to see if it makes this fast heart rate go away. Maybe I should try it for longer and live with the slight weakness to see if these crazy symptoms go away.

I keep planning to see my general doctor, and then everything goes back to MG normal and I get busy doing other things.

Also, the rapid heartbeat thing seems to happen mostly when I am having good MG days and not so much when I am having bad days.

I dont know if any of this makes sense, all I know is that it makes me feel crazy...when my heart is beating so fast I feel nervous and my thoughts are going around in my head so fast I don't know if I even make sense. Right now I am feeling bad, this is as bad as it gets.

I want to add here that my stressful moments are not always big stresses, but sometimes little things that really shouldn't matter. I feel like something physical is making me feel stressed, rather than stress causing the physical symptoms.

Could I be going into some time of short term remissions(or at least really good days) that last 1 to 2 weeks and during this time I am getting too much Mestinon?

I feel like I am typing contradictory to things I typed on other days, and it might be true because I am feeling opposite of my usual day.

It has been 6 hours since I took Mestinon last and I am so tense and jittery that I don't want to go to bed. I am not tired at all. Something is wrong. I guess I had better just make that doctor appointment even if I don't feel crazy tomorrow, even if it is just to ask for another referral to a new neurologist who at least listen to me.

Thanks Annie, I hope you are feeling better.