Worms? eeeek! beginning to panick!?

right im staring to panick abit lol!

I Treated Felix,Dodger,Splodge & Spice in January for worms

i used Beaphar multi wormer for cats:

i gave them the pink tablet one week for (roundworms)

the next week a fawn tablet for (tapeworm)

and then the week after another pink tablet for (roundworms)

and then they dont need doing for another 3 months,

the only problem is Dodger took all of the tablets well. But Felix & Splodge, were both sick over the fawn tablet for tapeworm

and the last pink tablet Spice needed to take she refused point blank.

Well tonight as you do i looked at Felix's bum, and the fur down from her bum there was a white worm, got it with some tissue and i think it was alive!!!

I checked the other cats bums but they look fine.

But all 4 cats are not due to be done till April..

Well this time i want to use a spot on wormer, cause it will be easier for me and the cats, instead of using tablets, problem is will i have to wait till April?

or could i try the Spot on wormer now, but wouldnt i be over dosing?!

Thanks! x