A hand to hold please!

I’ve had pain down the side of my left breast and in my armpit fold intermittently for the past few weeks, I’ve also been having pain at the top of my left arm, again intermittently.  As I’m 29 weeks pregnant I had put it down to that at first, I also have a toddler who’s very keen on being picked up and put straight back down atm and as the left is my weaker arm I put it down to that.  
I stupidly googled it and was bothered as it seemed the pain seemed to be along where the lymph nodes are, so I have been to see the GP who couldn’t feel anything and advised to go back again in a couple of months if the pain is still there.  Anxiety got the better of me and I booked a private scan in the hope I would be reassured and told it must be growing pains due to the pregnancy.  I had the scan this morning and I was advised I have an enlarged axillary lymph node on the left side, seemingly where the pain is.  The measurements I’ve been given seem to show all aspects of the node are double the normal size.  Again, stupidly googled it and it’s come up metastatic cancer etc, queue the near nervous breakdown that I have cancer and it’s already spread.  I’ve been hopelessly searching for anything begin it could possibly be, but it seems because all aspects of the node are swollen it doesn’t look good.  I’m going to contact the GP tomorrow, but in the meantime was hoping someone else on here has had or knows of a similar experience and it was a positive outcome.  Sorry for the long post!