Black spots

Asked at Hot Peppers but got zero respon so I'll give it a shot here also.

Got black spots and areas on some Bell peppers but now it also started to show on Piri-Piri and Chocolate Scotch Bonnet, it appeared and spread quite rapidly in about a week or so.

I was hoping the culprit to be overfertilization but I'm afraid it's some form of disease? The affected areas are black (not brown, white or yellow) and look almost like burns. The watering is sparse and the weather has been sunny so it's it shouldn't be ideal for some fungus infection or something like that (I guess?).

Any suggestions or advice would be much appreciated.