Mbuna are tough but they don't make good cycling fish. They are sensitive to ammonia. You need to do larger water changes, 2-3 gallons is not enough for a tank that size. When I cycled my 55 gallon I was changing 40% daily during the ammonia and nitrite spikes. It was a lot of work making sure the fish survived.
Bingo......
Yeah you should be doing close to 50% water changes daily to get through this spike.
remember when you do a 50% water change and your ammonia is 1.5 it'll only bring it down to .75 ppm then you should really do one again to bring the levels down to .375 which is still a bit high.
but if you do a 75% water change you will bring your ammonia down to .375
It's alright that you made a mistake everyone makes them. My suggestions is to do a 75% water change and try to keep the ammonia as close to 0 as you can. Good luck.