I don't like going outside anymore

There could be a few reasons that's happening.  If you are afraid of leaving your home and going other places, that may be an anxiety response.  Not all people who feel this way have all the criteria for agoraphobia, but that doesn't mean it's not hard and doesn't interfere with your life.  This may be triggered by a fear of being around people or people seeing you.  It may also feel like leaving the safety of your home is too overbearing without a clear indication as to why.  When it is the latter, it's typically brought on by an anxiety disorder (such as panic disorder).

If you have lost interest in going outside, that may be a very different clinical picture.  Did you used to enjoy getting outside but now feel like it is no longer enjoyable?  Have you lost interest in other things that you used to find joy in?  When depression is the culprit, it can feel like you don't get excited about things you used to like, which is also accompanied at times by feelings of worthlessness, hopelessness, sleep and eating changes, and frequent sadness.  

It's not uncommon for anxiety and depression symptoms to coexist, so you may be experiencing a little (or maybe a lot) of both.  If you feel like you need to speak to somebody about what you are going through, counselors can usually help and with the option of telehealth (online counseling) you don't have to leave your home to do so.

If you don't have access to a counselor, your primary doctor can also help you understand your symptoms better and maybe even recommend some other options for you.