Hi

this is a very long post so thank you if you read it all!

my son is 4, I took him to the drs in January due to him going off his food completely he would sometimes go a full day without eating anything and would always complain of his tummy hurting along with being very tired, on and off high temps, vimitting.. I expected them to tell me he was constipated but when examining him they found a lump in his left groin. He was sent for an ultrasound and blood tests and an urgent referral was made where he was seen by a consultant within 3 days, the ultrasound showed enlarged lymph nodes which they thought could be due to gastroenteritis which he had in October 21 and I was told they should have disappeared within 4-6 weeks, his blood tests showed low lymphocyte levels but they didn't seem concerned. Not much has changed since, his appetite has improved a little and he doesn't vomit as much but that's it. He was sent for repeat bloods and ultrasound around 2 weeks ago because at his routine appointment these lumps could still be felt. After his appointment I had a phone call from the radiographer consultant who seemed very concerned that his lymph nodes hadn't reduced in size and there were still a lot filling his tummy. They asked me to go to a&e where he had more bloods and was being prepped for biopsies to be taken to rule out leukemia/ lymphoma. 
All of a sudden a consultant came to me and said we could go home and there was no concern due his bloods being fine and the low lymphocyte level was still low but had improved, I asked why and the answer I got was that this wasn't an urgent concern all because the bloods were fine and I should wait for an appointment within 4 weeks with his dr to decide if they want to do biopsies. 
I am now just so lost, from what I've read blood tests can't rule out lymphoma and I haven't received any appointment from his dr yet which is making me more anxious that they are leaving it longer. I am having nightmares every night because I'm so beside myself wondering if this is going to be bad outcome now they're leaving it so long.

am I over reacting? Should I trust that they have done the right thing or should I demand the biopsies be done? 
thank you flew reading