Weight-lifting for the first time could definitely be the cause of dizziness/paleness. Try doing body weight exercises (try to get him to work up to 25 pushups without stopping, 5 pullups, and do some ab stuff, it couldn't hurt) and light dumbbell exercises (bicep curls, tricep curls, military presses, wrist curls with dumbbells under 30 lbs) for a while just to get a feel of muscular exertion before moving back onto the weights. Also, does ur husband not breathe in when lowering a weight and breathe out when pushing/pulling the weight? If so, holding his breath could be causing the dizziness

Does he have any conditions we should know about? Diabetes, anemia, anything? Would you say his diet is well rounded? Imbalance of proper nutritioning could lead to the problems you specified.

For the moment he needs to take it very slow and easy obviously, he needs to find his own limit, understanding what is too much and what is too little. Don't have him set goals like "I'll do this 30 times and then rest" or "I'll do this much weight", it will probably lead to overexertion and cause those exercise induced nausea. Whatever he can do where he feels like he got a bit accomplished, but not deadbeat on the floor because he did one too many sets and throwing up. What are your trainers saying?

And yes, you should probably check to see if he is holding his breath, it is a bad habit that could lead to feeling lightheaded and possible blood vessel ruptures.