You most likely have a gum infection, I recommend visiting your dentist, changing your toothbrush (every 3 months) and floss daily, brush your tongue. It's definitely time to immediately visit your dentist. Infections DO NOT go away on its own.
I don't brush , but whenever I do , I get these small white swellings that feel like an infection. What are these?
More than likely gum disease like gingivitis .. If it only is noticeable after you brush it's probably just more irritated because you brushed (and my guess is, you've probably brushed with a heavily bacteria contaminated brush) . Poor oral hygiene will most definitely result in oral issues.
If you have white spotting on your teeth it's an early sign of tooth decay
Seeing a doctor or dentist would be your best bet, but you might look here: