It's unlikely this is the case for you, but when I had trouble balancing in 2021, it turned out that there was a rapidly-growing lesion (metastasis) in my middle spine, crushing the nerves in my spinal cord.

If it keeps getting worse — and especially if your toes or behind start to get numb — go DIRECTLY to the hospital emergency room (ideally one big enough to have a good orthopedic and/or neurology department). Don't wait for a doctor's appointment the next day. My emergency surgery happened with only hours to spare.