Hi & welcome!
You probably have fungus gnats, vs. fruit flies. Investigate using BTi in your water to get rid of those:
https://www.google.com/?gws_rd...
In addition to probably preferring more light, the soil may need to be replaced now, or soon. Over time, the organic bits decompose into smaller bits, creating a mud that can suffocate roots because the particles are so fine and fit so closely together that roots can't get any oxygen. If you find a pancake shape of roots @ the bottom of the pot, chopping that off should make it a lot easier to remove the old soil, and often fit back into the same pot.
