Watermelon growth

Hello everyone!

I have Crimson Sweet watermelon plants growing in containers. About two weeks ago, I noticed that they stopped growing flowers, and all the ends that carry flowers started to dry. There was one watermelon fruit on each plant.

- Did the plants stop growing flowers to focus the energy on the fruits? Or is there something wrong with the plants? Are they supposed to continue to flower all the season or does it stop after there are several fruits?

- They also became a lot weaker overall (yellowing leaves...). Is it because there is not enough nutrients anymore in the soil, because fruiting is "consuming"? I would like to add some compost but now the top of the container is quite crowded with the vine and leaves, and I can't really access the top soil without risking to damage them.... 

- One of the watermelons burst open last week (It was the size of a grapefruit) so I had to remove the split fruit. It was the unique fruit on this plant, and all the existing flower buds have already died. It doesn't seem like it will grow new flowers again. Is there any chance to see new flowers again? Or is it then end of the "season" for this plant? 

Thanks for your help!