Three month old has lump on back of neck

My Three month old i notice has a small lump almost pea size on the back of his head, almost where the neck and head join. It moves around freely and does not seem to bother him in any way but i am obviously concerned as a new mum. Does anyone know whether this could be someting to worry about or is it something that generally can happen. I have thought maybe its a gland etc but am not happy with not knowing for sure.
Im planning to get him to the doctors next week but as you can imagine until i can get him there i am going to worry about it.
Can anyone help?

[RockRose]

Sounds like a swollen lymph node.  If the baby gets a cold or some other minor viral infection,  the lymph nodes can swell.

Best wishes.

[meiram]

My friend's baby had something like that develop right after she got her immunization shots.  Of course she freaked out and took her back to the doctor who said it was a swollen lymph node.  The doctor said that swollen lymph nodes are quite common.  

[Libi]

My daughter had something like that when she was just 6 or 7 months old. They scanned it but it was nothing, just a part of her neck. Freaked me out! It wasn't noticeable but I noticed it cuz I checked out every inch of her little body. Chances are it's nothing  but get it checked out anyway.

[tmv]

I agree, sounds like a swollen lymph gland. They swell as a sign that they are actually working to prevent illness. My ds had one for almost a year.