Thats the problem with people buying cichilds from fish stores, they get the impression they are compatable especially when the cichilds are juvies. When they become adults the africans will kill the other fish.
Not to mention african cichilds and convicts are from different lakes, and sides of the world. The african malawi's have to have high
pH hard water, the convicts like softer more acidic water. So you are keeping one or another in an enviroment they will not thrive in.
Also I noticed your tank has only been up for 7 days, its not cycled. You need to buy a
test kit and test the quality of the water. When you see the
ammonia/nitrites spike w/ fish in the tank if they live you need to do waterchanges everyday until the cycle is over (can take about a month at longest).