Concerned about a lump in my rabbits neck

Question
My name is Lovisa and I'm 17 years old. I have a rabbit who's approximately 7. Since his little friend's death 9 months ago he's been alone. We we're worried he wouldn't cope well with the sudden change of moving (my mom is allergic to fur and they were only living there for the time being) and his friend since he was little all gone. Fortunately he seems to have managed quite fine, although I sometimes feel guilt of not spending enough time with him. The thing I wanted to ask about however, is not his lonely life, that I can manage on my own. The thing I'm concerned about is that he has a growth just behind his left ear. The first time I noticed it  was maybe 10 months ago. Since it didn't appear to change I didn't really bother to check it out,  andit didn't appear to trouble him either. Well quite some time passed without any difference, but a little more than one month ago I noticed that it had gotten a lot bigger. It is like a little 'bag' that sticks out about 1,5 cm. He has got a small wound on it, i think it is from scratching his neck and accidentally scratching it a bit too much. What I'm wondering is:
1. what is it?
2. Can it hurt him?
3. Also, what is the minimum of time I should play with him each day so that he doesn't feel lonely? He has a fairly big outdoor cage so he can run around if he wants to, and we give him branches and things to play with.
I am aware that I should go get it checked out by a vet, but I just haven't had the time and I've been away much of the summer.
I'm glad for and answer.

/Lovisa

Answer
Dear Lovisa,

Sorry for the delay.  Had a few days of preparing for Tropical Storm Fay, which--when you have to wrangle 20 wild jackrabbits and 2 cottontails into the house for protection, you lose a few days of your life.  But all is well.  

Without seeing the lump, I have to make a guess from your description.  But if this is at the base of his ear and he's scratching at it, there's a good chance he has an ear abscess that must be treated by an experienced rabbit vet.  Please use the list linked here to find one:

www.rabbit.org/vets

Rabbits are very subtle about signs of illness and stress, but the loss of his friend could have contributed to a bit of immunosuppression that allowed this infection to take hold.  If you want to consider letting him choose a new pal, you can find your local rabbit rescuer here:

www.rabbit.org/chapters

(if you're in the US), and this person can help you do it the right and safe way.

Rabbits are most active at dawn and dusk, so playtime is best then.  It's hard to say how much time you need to spend with him to make him feel less lonely, since each rabbit is different.  But you might consider allowing him to choose a new mate, just to be safe, and to help him feel happy and well.

Hope this helps.

Dana