Garden News free tomato seeds help please

Hello
I sowed some of the Maskota? cherry tomato seeds that came with Garden news. they are now about 7" tall in their own pots on the kitchen window sill but they are turning brown and dry at the end of the leaves . New growth is fine initially but then starts turning. The leaves are also curling .They are aslo starting to flower. They have been like this since I pricked them out. :cnfs:I have given them a weak feed of tomorite today.
I grew the free seed from gardeners world last year and they were fine.
Can anyone shed some light onto why?

Thanks in advance

 

Could the roots be restricted, or not be getting enough nutrients? I tend to grow mine in the peat pots, and just plant them into growbags this way, although this will be my first year doing so

 

Thanks for the replies but not waterlogged or restricted. They are in individual 3" pots