What is wrong with my tomato plants?
There was little white egg looking balls that I had to use a hand lens to see. There was also little see through partial holes, and leaves turning yellow, which I kept plucking off. I got an insecticide spray, and drenched the plants few days ago. Now the leaves have dark purple spots, and seems to be spreading.
Certified GKH Gardening Expert
That looks like spider mite damage paired with a fungal infection.
This tomato is on its way out. Even with treatment, the damage has already been done, and the plant will never recover properly. You will have to replant.
There are several things that you will need to do differently next time: I would use a smaller container, until you see roots out of the bottom. Then you can switch to a container that is a little bigger. Keep doing this until they reach the size that you want. Then let them get rootbound.
Sizing up to big too fast will lead to infection. Usually they can fight mites off to an extent, but if there is an underlying issue then there will be no hope. Too much soil for a small root mass will mean that it stays wet for too long without any roots to take up water. This leads to infection. Using DOLOMITIC LIME and WETTABLE SULFUR in the soil can help prevent infections to some extent.
Spider mites are another issue. Once they set it, they have already infected your plants just by biting them. The tomato will suffer from permanent infections and eventually die.
Now, we have a few articles that will help you in the future: