a sprayed a little of a solution of dishsoap, vinegar and water to the plant, but I have no idea if that was the best thing and what to do!

Never spray with vinegar. People use it as a herbicide. In fact don’t use any home brew concotion unless you know what you are doing and what issue you are treating.

Sadly, it’s not possible to tell from the pictures what the problem is. But you could start by removing dead material and then rinsing the plant thoroughly under the tap. Sloosh the leaves with your fingers under running water. Repeat every couple of days until the plant is clean.

dish soap is often a detergent ... and is also NOT recommended ... though if thinned enough i suppose it could do little harm ...

dont confused dish soap with horticultural soap ...

you tried something.. give your plant at least a week before you panic and keep doing more ... but do keep observing.. and watering properly ...

ken