Also, the reason they may not be easting the veggies is because they've been fed an algae wafer every day
Try not feeding them for 2-3 days, then put some blanched veggies in. If they are used to only processed foods, it sometimes takes a little incentive (starving) to get them to eat.
You can get an API Master TEst kit which will tell you ammonia, nitrite, nitrate, pH and high pH for about $20-25 on [Ebay Link Removed] GH/KH tests are separate but I do think the master test kit is the bare minimum you should have with shrimp. I know what it's like being a on a budget so watch the For Sale section here, some folks will often sell little used tests kits for good prices.