Agree with the advice on getting a bike fit. Even if you decide to get a new bike, it's a good idea. Several years ago, as I started increasing my mileage and ride difficulty, I was getting to the place where I was getting sore in a number of places ... had knee pain, elbow pain, back and butt were sore. I got a bike fit and they did a few things ... swapped out the handlebar to a narrower size (which resolved my elbow pain) and adjusted the saddle position and the cleats on the shoes, and adjusted the handlebar height/reach to a more comfortable position. Then, I had a habit of inflating the tires close to the max psi so I reduced that some to make the ride less harsh. I also experimented with a few different saddles and settled on a Brooks leather saddle, which for me, provided a great deal of comfort. I did end up getting a new bike (Trek Domane) that felt like a less harsh ride than the old bike, and carried over all the above changes to the build-out. I'm 66 now, so a similar age as the OP.

Good luck