Can you please tell me why god allows my husband to suffer horrible pain from lung cancer and cancerous tumors on his spine?

He can get help. I am sorry to hear of your husbands pain and how it is impacting his quality of life. I would highly receommend that he see his physician and possibly someone from pain and palliative care. We have a wide array of medicines to control pain. Radiation may also be an appropriate option depending on the circumstance. I hope he feels better soon.
Theology; not medica. Defining "higher power" is hard, and being angry at suffering and death is human. I hope and pray you and your husband can get relief and peace now, and when his suffering is past, you will mourn and find comfort from his life. God is not suffering and pain, but love, beauty, justice and fairness. Evil exists in pain and denying comfort to the afflicted. Find help at hospice!
Is God your Father? These are very, very difficult questions. Since I had my first child, though, I think I understand god better. Remember when your child wanted ice cream? So you gave him some. But then he wanted more, and you said no? Was that because you did not love him? No. It was because you knew more than he did, and even though not having more ice cream seemed bad, looking back, it was not so serious.