White or green water ?
If you want to see if it's a bacterial bloom, put some of your water in a white bucket, then look if there's a little green tint, or if it look more grey/white.
If it's a bacterial bloom (grey/white), then watch ammonia to be sure there's no rise, there's chance you get a spike if not already done. If you get an ammonia spike, do a 50%WC (this should reduce ammonia by 50%).
This week my water became so couldy we can't find fish, and I was sure it was bacterial bloom because the grey coloration the light was giving... After I have put aquarium water in a white bucket, this way I understood it was algea bloom.
If you have an airstone and an airpump, it can be the time to put it in water. Thoses bacterias are big oxygen consumers, and ammonia burn the gills of the fishs and make them suffocating because oxygen is less absorbed by them. An airstone can accelerate or maybe help the developpement of your cycle. By increasing surface agitation with airstone, you will result to have more oxygen available for those unlucky fishs.
If you don't have airstone and airpump, don't run to the LFS except if your fish are gasping at surface.
Some products can help to restore your nitrogen cycle... Some people say they work, some other say it doesn't work. In my opinion, I cycled a tank in 9 days with "Nutrafin Cycle" and a betta, it worked pretty well.