Strange lump on Asha's neck/throat

Hey,
I got home from work today to find my 18 month old springer x cocker spaniel had a strange lump on the underside of her neck/top of her throat, it defiantly was not there last night and I am pretty sure it wasn't there this morning so it has literally appeared within a few hours, the lump itself isnt attached to her neck as such as you can move it around but it is under the skin, the lump itself is quite soft and when I touch or move it Asha doesn't seemed too bothered by it, I have also noticed that between the lump and her left ear is quite swollen.
Asha herself seems OK she is eating and drinking and the tail is still wagging but she does seem a little quieter and notnher crazy usual self.

I was wondering if anyone has ever experienced a similar thing with their dog?
The vets are closed now but I will be calling in the morning just to get her checked out, better to be safe than sorry!

Any advice or info on anything similar you have experienced would be great as I am just a little worried and I just hope it's nothing too serious!

Thanks!
Emma & Asha x

Could well be a bite/sting.

That's what I originally thought but she will let me touch and feel it without pulling away at all so I would of thought it would be uncomfortable for her to have it touched if it was a sting or bite

maybe An abcess?

Could she have had a tick ? If mine have a tick it will leave a lump for a couple of days.

Raz had one there which turned into an abscess. I`d keep an eye on it and perhaps clip a little of the fur away to help keep it clean and dry? Watch the collar doesn`t catch it.