Can my landlord raise my rent to whatever he wants to?

Sign a lease with your current landlord...otherwise he can keep raising the rent every month. If he doesn't want to have you sign a long term lease then he's either trying to get as much out of you or force you out of the rental. I would look into a different rental and see what they cost... and look into moving. It sounds as if you are month to month...so just give him notice and move out at the end of the month.