Some kind of fungal disease.

Got a pic"? "wrinkled" could mean several issues. If these wrinkles are located on the bottom of the fruits then it may be "catfacing". At best these are good enough for salads. I'll remove catfaced fruits when they are the size of golf balls, no need to waste the plant's energy on them.

Looks like blight to me.

At this stage of ripening the fruit should still be quite firm, so if you push lightly on the affected area and it yields to the pressure (it feels mushy below the skin), remove the fruit because things won't get better.

It could even be BER. BER is a physiological disorder usually brought on by high N levels and rapid vegetative growth in young plants early in the season. Ber is quite common in containerized plants because over-watering is so common and limits Ca uptake, causing cells to form abnormally in the distal part of the fruits for lack of it. Your plant doesn't present the characteristic leathery spot at the blossom end that usually serves as the clincher insofar as symptoms go, so I would find it hard to find standing to argue with any enthusiasm against Windberry's diagnosis of 'late blight'.

Al

Bacterial soft Rot. The fruit will end up as as bag of foul smelling liquid.

http://www.omafra.gov.on.ca/IPM/english/tomatoes/diseases-and-disorders/bacterial-soft-rot.html

I agree with blossom end rot (BER) It usually happens to the first few tomatoes, then clears up (at least here).

Keep watering consistant.