I'm so sad nobody has responded to my post. Maybe I'm not enough of a victim ... .maybe i come off as too strong ... .I have no idea other than to say I was never willing to accept being made a blame-ridden, guilt-harboring, self-deprecating victim to this. Yes, I'm capable. Yes, I'm fighting it. Yes, I'm experiencing all the heartache here. Considering signing off because maybe I've picked up ticks or maybe I'm finally saying non-support when i spill my guts is not enough.
You're asking a question about relocation. Some people may not have experience with this. It's not personal.
In my state, the court has a list of criteria it uses when a parent files for relocation, at least -- that's the case for an out-of-state move. You can probably call your clerk of court to see if there is something similar where you live. The criteria here is stuff like: will the child be in a better school, is the parent moving for a job that pays better, will there be family members nearby, etc. Focusing on better medical attention for your child might be one of the criteria where you are.
My guess is that moving approx. 50 miles away won't be an issue. Some parents move 5 hours away to another state or farther, so parents do this all the time. Like FD said, probably won't be an issue if it's just moving out of the county. If your ex makes an issue of it, he might draw attention to himself for being unreasonable.
Do you have an attorney? You might be asked to pull together documentation that shows how many doctor visits you've had to go to, how much time it takes, how much it costs in gas.
Try to avoid mentioning that ex's mom spies on you, etc. Courts don't want to hear that stuff. They just care about whether you are focusing on what is best for the child, and how things impact their well-being.