Put a potato slice on the top of your soil. If you hsve aphids, they will go to the slice.
You can get a small cup full of soil, run 7.0 ph water until you get a little run off. Check tbe EC, and ph.
If it's not bugs, too much nutes are in the soil, that will do a few bad things, including throwing off your ph, as well has putting your ec at way too high a level (they go hand in hand)
Are you feeding salt based nutes?
You should either give a good flush, and stop feeding (only ph'd water)
First get the results of the runoff. Also check when you flush.