Is Hodgkin's Lymphoma A Possibility Here?

I'm a 46 yr. old premenopausal woman, enjoying life as a piano teacher, with relatively little stress, compared with the days of nursing my parents years ago (my mum died of High grade gastric Non-Hodgkins Lymphoma, aged 57). I've lost quite a lot of weight, sometimes get night sweats, and I can see a lymph node about the size of a pecan nut in front of my left clavicle. My 22 yr old son who is studying 5th year medicine, and reckons he can feel a couple of large ones. One is nearer my neck, in my left shoulder, though I can't see them. I have been getting pain in that shoulder and in the arm with hand weakness. Last evening the veins in my wrist and hand swelled up for a while and I felt rather weak, with palpitations. And kept waking in the night with odd sudden thumps of the heart. I wondered whether I had a constriction of blood vessels in the arm or a separate circulatory issue. Do you think I could have Hodgkin's Lymphoma, given that several blood test results are acceptable, a GI endoscopy 2 weeks ago was all clear, except I still had porridge oats in my stomach 7 hours after breakfast, so they asked if I was diabetic and a fasting blood test proved negative. My chest Xray 3 weeks ago was clear, though an abdominal ultrasound scan last week showed a small non-shadowing 3.7mms hyperechoic focus near the posterior gallbladder wall. I sometimes have trouble emptying my bladder, so for the internal womb ultrasound,I had supposedly emptied it but the ultrasound showed that it still contained 168ccs. I am a pianist, and have been afraid to play in public recently, as I tend to lose a bit of control of my bladder, (and sometimes at night) though that is more of a minor issue as far as I'm concerned, at the moment. I have an appointment booked for a neck ultrasound on 13th June, but would like someone's opinion now, if possible on the seriousness or otherwise of my condition. Thanks.