I actually started running in my 50’s and for 3-4 years it was great. Then the maker of my best shoes decided to change their Cadillac to Cruz - and my running suffered greatly as did I. I have found the proper shoes by a different maker and that made a huge difference. However - I still couldn’t sustain 2/3s of the distance I previously ran on any given night and running in the cold which had been a fave was right out. In talking to friends I decided to try inserts. AMAZING! In my first run with them I sustained my mileage at what it had been but without stops and at a faster pace (I would not consider myself fast by any standard but I was faster than pre-inserts.) The next day I added a half mile. The next day I added another half mile increasing my mileage by a mile in two days. While my legs felt worked they were not sore. No hip, knee, ankle, Achilles or back pain. I took comfort in knowing my cardio was there all along - it was other issues interfering in my ability to make sustained runs. 

I don’t know your issues or thoughts but you may want to check out your feet. They change with age and miles. They can be the last thing considered too. 

I don’t know if this helps but I wish you all the best and a resolution to your issues. Nothing beats being able to get back out there and enjoy the mind clearing freedom of a good run. Take care!