I have used the amquel plus when ammonia or nitrites were a problem and it seems to work well. Just know that if you test your ammonia with a 1 part test (yellow to orange), your results will be inaccurate. You must have the 2 part ammonia test (yellow to green), or your results will be incorrect.
As far as the bio spira goes, if you are still having problems down the road, and you would like to try it, make sure the dealer you get it from is reputable. Mishandled bio spira will be an expensive package of dead bacteria. What I did when I had a cycle emergency was to remove the fish, drain the tank, refill the tank, add the fish back in, and then add the bio spira. Bio spira is not meant to be used to play catch up, so draining most or all of the high ammonia or nitrite water allows the bio spira to work in a level playing field, and is not overwhelmed by the over abundance of the ammonia or nitrites. It will catch up eventually in a tank, but not necessarily before your fish die, so it's better to use it when the ammonia and/or nitrites are at an even level so it can maintain the tank at a cycled level.