You've said that you didn't suffer from anxiety issues before smoking weed, but uswed to smoke a lot of weed; thus is could definitely be a side-effect from your time smoking. How long were you smoking for and how much did you smoke?
Unfortunately, some people do experience adverse effects from smoking marijuana and you may be one of them. How long ago did you quit? It may be that you are experiencing social anxiety and/or generalised anxiety (which this sounds like given your short description), which is certainly not an uncommon side-effect from stopping heavy use.
It would be a good idea to go & see your doctor- he/she can prescribe a short-term anxiety medication, which may help , or alternatively, look up Cognitive-Behavioural therapy on the internet. If you can afford some type of therapy sessions with a good CB therapist- that may also help. Another avenue to try is self-help; watching your diet (caffiene, comfort food & stimulants- bad; fish, herbal teas & fruit & veg- good), introducing regular exercise & sleep routines, meditation, etc.
Sufferers with anxiety problems have a thought-process known as a looming maladaptive thought-schema. If an experience turns out to be a bad/negative one, it is then avoided & shear thought of a similar circumstance sets of a pattern of negative, doom-laden thoughts. Developing a resistance to leave comfort, safe areas (like home) is certainly common with lots of phobias.
Going to see a doctor- no matter how scary the thought of leaving the house is- would be your first step in trying to overcome your anxieties & get back to your old self (without the weed).
You don't have to tell the doctor you smoked weed, if you don't want to. Lots of people suffer with anxiety in one form or another and there are a number of ways to treat it.
You are not alone & you can overcome it.
Good luck & best wishes.