I Think I Have Been Ddosed

I need help.
My office runs on 15 systems connected to a server. Our website is also hosted on this server. From the start of this week, we are facing occasional network freeze for a few seconds. Then, I came across this blog http://nci.ca/what-you-need-to-know-about-ddos-attacks/ and when I checked our server, I found that there is huge spike in traffic. I think I am a victim of DDoS attack. Do you think these symptoms are result of it? What should I do now?
Need your suggestions and help.
Thanks.