Maybe you can give yourself a time limit? Allow another few weeks to hide and then bring it up with your mother?

A simple "Mom, can we talk?" can go a long way. You can start by telling her that you're stressed all the time, that you think it's gone beyond what normal anxiety should, and you'd like to get a doctor's opinion. If you see a doctor he or she can help your mom and you go over ideas and options from there on. It would definitely be an adjustment, but I know you can do it.