The big bulb alliums are winter growers, so feeding or repotting really should be done in late autumn.
If yours still have decent leaves or are not the big bulb types then yes feed them now.
Try with a feed which is taken in through the leaves if you have it.
You could scrape off the top of the compost down to the bulb level and top up with fresh compost.

Thank you Owdboggy , they are Millennium and flower about August so I will feed them , thank you for your help.