Breast swelling after lumpectomy - caused by weight lifting??

I had a lumpectomy in July with six sentinel nodes removed.  I've asked the BS, 2 MOs and 2 ROs about the possibility of lymphedema, but all of them have told me that it isn't very likely and have pretty much dismissed the idea.

I'm now in the middle of radiation.  By the 2nd day of radiation, the affected breast was swollen, tender, and pink and it is still that way after two weeks.  The RO says that it will probably be that way until several weeks after radiation ends and that it is probably due to the fluid that is filling the cavity left from the lumpectomy.   He isn't concerned about it being a problem.

The nutritionist is suggesting that I do some light upper-body strength exercises with 2 or 3 lb weights and the RO says that it is a good idea, but I'm concerned that it may put me at risk for lympedema if it is repetitive motion.

Does anyone have any thoughts on this?  I hate feeling as if I'm in limbo! 

Weightlifting can (not necessarily will--we all respond differently) help lower LE risk of the arm, and the logic is that when we lift something heavy, with weight we are not accustomed to lifting, the challenge to the muscles signals stress to the lymphatic system. So, if we build our strength -gradually, slowly, carefully- lifting something heavy will not be 'unaccustomed' and the lymphatic system will not respond to perceived stress with a build up of lymphatic fluid being sent to the rescue. The trick is to not trigger LE while doing the weight lifting! Several studies have confirmed that weight lifting per se does not increase LE risk, but only if you do it following very careful and cautious guidelines for slow, gradual addition of weight.  It's not a cure or a treatment for existing LE, although many women find that when they're stronger, they're less likely to have LE flare ups after physical exertion.  

One more thought is that muscle movements against the lymphatic vessels moves lymph along in the body, so to the extent you're using muscles, you're enhancing the lymphatic activity.

Here are two documents to look at and to show your doctors, etc. They're similar-one is for personal trainers and exercise instructors, and the other is for women who have or are at risk of LE and want to learn about exercise precautions.

http://stepup-speakout.org/Trainer%20doc%20for%20SUSO-040113.pdf

http://stepup-speakout.org/Handout%20doc%20for%20SUSO-040113.pdf

The landmark PAL Trial (Physical Activity and Lymphedema is what PAL stands for) had women start with one-pound weights, nothing heavier, so I find that a recommendation to start with 2-3 pounds is aggressive.  Think too, that when you put a weight in your hand, there's a lot more resistance against your torso if you extend the hand out compared to holding it into your torso, another reason that starting with very small weights is a good approach.