I'm sorry to hear that. She should NOT be getting overheated or be out in hot weather. "Hot" for me is anything above 72 degrees, if it's outside.
What extremes of heat and cold do to MG is that they increase the enzyme in the body called Acetylcholinesterase (AChE). In any body, acetylcholine is sent to the muscles. Then AChE comes in and mops up the excess amount. It's a perfect checks and balances system. Well, unless you have MG.
Mestinon keeps that enzyme from mopping up the ACh so that we can use our muscle gas for a longer period of time. But when you get too much of the enzyme from being out in extremes of heat and cold, it's harder to keep it from doing its job and we get less acetylcholine.
Does that make sense? Bottom line is to keep her from getting overheated. That would include fans, cool packs (like Boo Boo Buddies for kids made of gel) and drinking plenty of fluids. Getting infections can heat up the body too, so keep that in mind.
If your daughter can't move well, is having trouble breathing or can't swallow, it's time to dial 911. Don't be super Mom and bring her in yourself! It's important to get that care immediately. I'm not saying this to scare you! MG is manageable but you need to know what to look for and how to handle it.
I know it's hard watching your child be sick. But, again, you need to try to stay as calm as possible. Knowing that MG gets worse when someone does something and better with rest, you should schedule more rest periods during the day. Like reading time or anything else she likes to do. Naps too!
Does she let you know how she's doing? It's also not only after activity but towards the end of a day when things can get worse. And MG is odd. You can overdo it one day and have "payback" one or two days later. It's a really frustrating disease sometimes. She should not push things physically at all. If you push MG, it just pushes right back.
She's instinctively managing her MG already. What she probably needs to do is stop activity a bit sooner than when she gets worn out.
If you need any more information, please ask. One thing I'll say is that Mestinon syrup might be the way to go with your daughter. You can titrate it more easily. She might need to start with a super small dose like 12 mg (which is 1 ml) and work up from there. This is advice from MG experts!
So if your docs don't have this experience, they may tend to go for the big dose of 30 or 60 mg. right away. She might then have overdose symptoms. So you might need to go slow at first. At least have this conversation with them. Also, Mestinon only lasts for about 3 hours. So realize that this dosing schedule should be written down. It's easy to forget!
Mestinon syrup tastes like a less tart raspberry. It's not a bad taste at all! It does have 5% alcohol though. That's not very much. It's what I take and I like the flexibility of the dose adjustments.
I hope you'll realize that MG can be managed well. You'll have to take the lead on that though. As long as you make this new thing for your child like brushing her teeth or anything else "normal," she'll adapt well to it. Kids always amaze us in their ability to deal with things.