Feed not working properly after DDOS attack

I have a blogging site, which I was hosting in a shared server. Suddenly it had DDOS attack and after this I transferred it to a VSP. The feed of my blog was getting fetched by some other websites, but after this incident some of them were unable to fetch the feed from my website. one of them suggested me to change the domain name, I did that too. But its in vein. Can I get some guidance to solve this issue.
Mine is a multisite, and wordpress version: 4.2.5