Is having vats resection if a spine tumour considered major surgery? It's been three weeks I'm still in agony where the chest tube my nerves hurt too

Yes. Vats is major surgery. Unfortunately, pain from chest tube site and/or vats instrument port sites can result from intercostal nerve injury/compression. Some patients may suffer neuralgia following surgery.
VATS tumor resection. Three weeks is still very short in the recovery process and hopefully you are noting a slow but steady improvement. Without knowing the details of your surgery, levels treated, method of reconstruction, preoperative symptoms, etc., it is hard to know whether there are any new concerns. Follow up x-rays may demonstrate a symptomatic pleural effusion for example.