Lump in 3 yr thigh lumphnode

My 3 year old son has had a weekend ammune system for as long as I can remember, he's struggled with sever anemia and low red blood cell count. He recently has developed a large lump in the lymphnode in his thigh, along with worsening of other symptoms he's struggled with such as extreme tiredness, facial flushing, scratching (mostly at his face), I assumed this might have been due to allergies of somekind but giving him Benedryl has given him no relief. He's also complained about constantly being cold but has been experiencing horrible night sweats, where his clothes and body are literally soaked when he wakes up, he's appetite has decreased and he complains of tummy aches all the time. We went in to get this lump checked out and I assumed his iron was going to be extremely low, assuming the being cold and exhaustion where due to that but they weren't. They did an ultrasound and saw the large mass in his lumphnode and put him on an antibiotic to see if it would make it go away, after 10 days no change at all. It doesn't seem to hurt him at all whatsoever but slowly seems to keep getting larger along with a fever that comes and goes and doesn't make any sense at all to me. We met with a surgeon ans he wants us to wait another full month (it's already been a month since we discovered the lump) before he wants to remove it by putting him to sleep and removing the entire mass, and do a biopsy of course. I have to saw I don't feel good about this at all and my gut is telling me there's something more going on here, has anyone else experienced this and is it a good idea to wait another 30 days to do anything? Please any input or suggestions would be greatly appreciated, could this be something serious and should I be worried?