terrible cold symptoms followed by tiredness

Hello - first time poster here. Last year right around New Year's Eve I started with a horrible cold. It had different stages. It went from horrible sore throat to sneezing like crazy to not being able to breath to incredible head congestion (heavy head)... and then when the cold symptoms finally went away I was tired and feeling "knocked out" for literally a full month afterwards. Well, it's almost like clockwork because just last week on New Year's Eve I started with it again.. and I hadn't been sick since. I went to the doctor after the first day and was tested for strep but I was told I didn't have that. I also have not maintained a fever so I've ruled the flu out. It's been almost a week and have re-lived all the symptoms I just mentioned. Today I finally feel at least like I'm half of a person mentally and physically, but I'm extremely tired. Can't sleep enough it seems. Now I'm worried that I'm gonna have that month long tiredness and light headedness I had last year. I still don't have a fever though. Has anyone else experienced this? What in the world do I have? It's gotta be more than just the conversational "very bad cold" that seems too simple of a diagnosis to me. Any words would be greatly appreciated.