Hi, sorry to hear about your fish
There's a great article pinned here about cycling ur tank to get the water good for fish before u put any in there. I read it a tad too late, and even though i didn't lose any fish while cycling, they would have been a lot happier & healthier if I did things a bit differently lol.
I don't know that there are any cichlids that won't dig up ur plants, but maybe if u try the plant varieties that u can tie to a rock or cave, I'm not too sure on that one. Cichlids r great, loads of personality, but I have a feeling they're best in a larger tank (not sure how big urs is). They can also be agressive so watch what tankmates u put with them.
Also, if u didn't know this already (I didn't till I read it here lol) - there are a lot of medications u can get at ur fish store to kill paracites, infections, etc. So long as u follow the instructions, & r sure what's wrong with the fish, they should work ok (just in case something similar happens again
)
Anyways, someone else will probably be able to give u a lot more useful info than this newbie. Goodluck