Can I add veg nutes even though iv went straight to bloom nutes when switching to flower

I just switched to flower and went straight to bloom nutes. My leaves started turning yellow but I read that it's because I'm suppose to keep feeding veg nutes for couple weeks into flower so can I just add that in seperatly just now or do I need to flush then add it

You could do it two ways either revert back to the veg nutes on next feed or flush then feed veg nutes for 2 weeks then add bloom nutes after are you in coco or hydro?

Should I wait few days after the flush to add veg nutes or just give them it straight after, just don't want my leaves all going more yellow. I'm in soil 20l pots.

Providing you flush the soil thoroughly I'd wait a few days let it dry out somewhat and then start feeding nutes again

personally i wouldnt flush..
its a little hard on...everything

you could foliar, next time it needs water just add more n. i normally use the same nutes start to finish

Just add veg nutes to your next feeding along with your veg nutes.