muscle tightness in stomach and throat

Does anyone know how to relax the muscles tightness in the throat feels like something is pressing on it and makes me gag and also stomach tightness.....

it would be good to relax the entire body to get rid of the tightness in your throat and stomach. Something that always works for me is meditation and listening to a talk on relaxation for anxiety. You can find these on YouTube. Also listening to proper breathing for anxiety really relaxes everything.
when anxiety level is high, everything tightens up it could be your throat, stomach, back, head, shoulders etc. The anxiety level needs to be brought down in order for you to feel better. Another thing that helps in a huge way is gentle yoga which can also be found on YouTube. Getting some exercise gets rid of anxiety and heals the body. Take care of yourself

Listen to Jan34534 for relaxation techniques for easing the tightness. If that doesnt work, a benzodiazepine might be the solution you are looking for. Call your doctor and ask for one as there are a few to choose from. In the meantime try to relax your mind and body like Jan suggested.