it's probably nothing serious, unless you really haven't brushed your teeth consistently for like ten years.
If anything, it's most likely gingivitis, which is a reversible moderate form of gum disease. The symptoms are really just inflamed / swollen gums and bleeding while brushing. Gingivitis is reversible by just simply brushing and taking care of your teeth in general, it's advised you visit an orthodontist for an actual inspection as there isn't much I can draw from the information you've provided. Also, it's obvious I'm no professional.