I have a small lump below my knee hard and pea size been to doctors says it's a cyst docent thing its nothing to worry about but to keep looking to see if it gets ene bigger or hurts but now I carnet stop worrying should I go back to the doctors

If the doctor said it is nothing to worry about then it shouldn't be.
Cysts often are nothing to worry about.

If you feel uncomfortable about it, get a second opinion if it would ease your mind.

Getting a second opinion will help you to stop worrying. If the second doctor agrees, and there are no changes, then don't worry. Just keep an eye on it and have the doctor take a look at your next physical. As long as you check it and go to the doctor for your checkups, you should have nothing to worry about.