Asking for help makes us feel vulnerable. It also means unlocking doors we thought we had sealed tight. It also means giving up a little control and that's not easy.
It is hard to feel so alone and afraid. There is help and it's is never a burden to those who love you. You really are not doing the people you love any favours by not involving them. In fact when it all bubbles up, and it will eventually they will feel guilty and sad they didnt notice and you were not able to trust them. There are people who like feeling useful, to be of service to others. Think about who might best respond with compassion and listening. There are ways to treat your concerns without meds but if a medical profesional thinks it might help it could be your saving grace and actually help you feel more like yourself instead of the victim of your uncontrollable thoughts. If youd broken your leg you wouldnt refuse a cast, in this case youve broken your brain. Its not forever and there is no cool thing for your friends to sign. Its all invisible and intangible. Try and educate yourself as much as possible about mental health issues so you canunderstand the monster you are wrestling.
And cats is right, the sooner you get the support you need the more manageable the problem will be. I hope you find what you need soon