I’m thinking, to be on the safe side that it might be a good idea to have your leg checked by a physician if the pain persists. However, I found this interesting article on Missouri Vein center’s website which explains leg cramps and lingering pain. According to the article it’s not uncommon for pain to persist for 2-3 days. I think you might find this helpful!

Why Does My Leg Hurt So Badly After a Leg Cramp?
https://blog.missouriveincare.com/blog/why-does-my-leg-hurt-so-badly-after-a-leg-cramp
I also found some information on the GM diet for you. There is controversy over its effectiveness long term and the safety of the limiting foods and the amount of water taken in because it can upset the electrolytes in the body.
https://www.healthline.com/nutrition/gm-diet
There are other healthier options for weight loss if you’re interested. Quite a few members in the forum have benefited from intermittent fasting. Here’s a link to the discussion.

~Low-carb healthy fat living. Intermittent fasting. What’s your why?
https://connect.mayoclinic.org/discussion/low-carb-healthy-fat-living-intermittent-fasting-whats-your-why/
I know it can be a challenge to lose weight and we want to do it as fast as we can for that instant gratification. As frustrating as it is, more often slow and steady wins the race.
Have you tried intermittent fasting?