My menstruation(haydh) is always 7 days. I shower on the 7th day and when I wake up it's a very very small spot. I dont think its blood it's not red. Do I need to do the ghusl of haydh or can I just change and keep doing wudoo and pray?

If the discharge is yellow and brown and there is a possibility of there being blood in it then you will need to do ghusl again