I will try to put things into perspective.
1 You have just recovered from long term pain & restriction in what you can do so you can expect your body to be less healthy than ideal.
2. You just started exercising at the gym so you WILL get better, fitter lose weight etc
3. If you haven't exercised for a while you can expect your muscles to be sore. That is normal. NOT something sinister.
Last year I was recovering from a series of injuries. I'd put on weight & when I tried doing simple daily tasks I'd virtually collapse. In other words I was VERY unfit. I didn't go to the gym & had no assessments but I'm sure if I had I would have had bad results & high risk of diabetes etc. I started walking initially very short distances & gradually increased it I also went on a diet focussing on eating healthy foods rather than any junk. Within 6 months my weight had dropped to a healthy level & my fitness was back to normal. Similarly my husband was diagnosed with high Cholesterol but unable to take medication to reduce it because of side effects. He also had lots of stomach fat so was at high risk of lots of disease. He went on the same healthy food diet as me & started exercising regularly. When he finally got an appointment to see the specialist re his cholesterol & high risk of heart disease he had another blood test & found that his results had all dropped back well into the healthy range. I am sharing this to reassure you that being told you are at high risk of diabetes etc today Doesn't mean you will remain at high risk. Now you are able to exercise again you can improve your health & reduce that risk. Just don't push yourself too hard. Allow yourself time to build up your fitness.
As for people like your MIL pointing out that you've put on weight. ignore the comments. You have just come out from a long difficult time. Now you need encouragement not put downs.
Good luck & I hope those sore muscles improve soon so you can stop feeling anxious about them.
