'street weed' is not the same as medicinal. It can actually increase your anxiety to the point of psychosis and paranoia.

There are multiple medicinal strains but they generally break down into two types:

a higher CBD - is the pain relieving, anti-anxiety, anti-nausea, muscle relaxant variety
a higher THC - is the 'high' and is sometimes used as an anti-depressant.

As you can see, you take a strain that is predominantly one or the other unknowingly and that can be a recipe for disaster.