I think it's okay. Maybe wait and see if it gets any worse?

Do you mean a big brown area? There is something called blossom end rot.
But in the photo it could just be the type of tomato, what variety are they
Some of the very big tomatoes grow like this I think

Thank you Fuzexi, & Pamg,I will go on to Google to see what blossom end rot is,the variety is called money maker.

Its not nice Johnjoe but not unexpected when we get high fluctuations in temperature, uneven watering etc, itcauses ...well the blossom end of the tomato to go black.....
I just take them off and hope for the best......

Yours doesn't really look like that though, yours looks as if its how its developed, are they all like it or just one plant?

Thanks Pamg,I only have 2 plants the other plant look OK. I did cut some leaves of it,do you think that could affect it.

I wouldn't have thought so, occasionally you do get odd things happening like two fused together or extra bits growing
If you look at tomato photo's on Goypedia there is at least one odd specimen. :0)

Thank you Pamg, I will have a look at that.