Internet speed please help

A couple of months ago I allowed a couple of friends to move in with me and my family as they have fallen on hard times. Things have gotten better but, for the time being this looks like it may be a long term arrangment and my only problem with this is the internet. Before they moved my internet was running 15Mgb/s on average now it runs about .6Mgb/s which as you can imagine makes gaming/streaming nearly impossible which sucks because I am a twitch streamer. I cannot upgrade my internet past its current point because of where I live is there anything i can do to fix this please help