I have a lump on my armpit, it is growing and irritating?

27 Years Old, Male, No medical history.

Main Issue:
– Swelling type of visual on armpit
– Starting to go red and irritated
– Feels tender, almost like Puss built up

Condition:
– Last week I felt I was coming up with a cold
– Friday 07 Oct 2016 I was returning home after a meeting and started to get cold shivers and bursts of hotness in my body causing sweating.
– Also had terrible cough turned flemmy quickly
– Suggesting a virus.
– I’ve taken medication (no antibiotics at this stage as this has started to improve 10 fold).

I have come to notice a few days ago a lump on my armpit and as I have started to touch it more often it’s started to grow and cause irritation. It feels tender and seems like I have some liquid built up inside. Not sure if it’s an infection or anything.

I have in the past shaved my armpits / trimmed but have never had this before.

I would much appreciate your response and suggestions of treatment.

P.S – the Image doesn’t do my description any justice but you should be able to see the red saw area near the bottom and going round to the middle. That is the location of the slight bump. It has certainly gone bigger since yesterday night but that may be because I kept feeling it and may have caused irritation.

Many thanks.