Thank you for all your responses. I've had my eyes checked recently and have new lenses but I had this problem before the new lenses so it can't be the glasses. I'm on medication for high blood pressure wbich hasn't changed for many years. I've also suffered with tinnitus all my life and must admit it's getting worse. When i mentioned it to my doctor she just said I'll refer you to the tinnitus clinic. I'm not sure if anything can be done about tinnitus.
I've never had a problem using escalators but the last few times I've used an escalator going up I've clung on to the handrail because I really felt I was going to fall backwards. It happened again today and I probably looked quite silly clinging on for dear life. Has anybody else experienced this. I've never had a problem before and was in admiration and envy of those that just seem to step on the escalator without even looking up from their phones.