I do push ups and planks every day but which is better?? Doing push ups first then plank or plank first then push ups?

You say you are doing the exercises everyday. If you are doing the exercises correctly and to a fair degree of fatigue, you should take a day in between to recover properly. The planks use high endurance stabilizer muscles and once well conditioned, these muscle could be trained more aggresively. But you should have a specific need to do so. That is, you are having issues with stabilizing your spine due to low endurance capability of these muscles. Then you may want to lower the volume (the total time spent doing planks) in one session and add more sesssions throughout the day. Starting with one 1 minute session with 3 to 5 plank holds. And then increase the time held for each one by 1 or 2 seconds, building from there. Even if you are already doing more than this, it is not a bad idea to restart the program and make sure you are doing each exercise correctly.

Since I can’t see you personally, a lot of this advice would include variations specifically to what you are doing and how. And there are many muscle groups that you apparently are not exercising yet. Adding pull ups is possible, but do so cautiously. Pull ups are very difficult to perform correrctly if you are not already strong enough to do them. Again, adding 1 to 3 pull ups every other day for a while before attempting more. And adding one pull up at a time for a few sessions is wiser than trying to do as many as you can right away. Working too hard too soon is a recipe for injury. Give your body some time to adjust and prepare for more intensity and volume.

I highly recommend you let your doctor know you are interested in exercising more and more intensely. It can’t hurt and it could save you a lot of hurt down the road.