Ok, you're gonna hate this but the muscles associated with the humerous bone are affected by the core and also by the rotator cuff muscles which are attached to your shoulder blades, arms and shoulder joint, proper. So . . we could be talking about bicep / tricep or we could be talking about the deltoids. The problem could be that the point on your arm where the pectoralis and the latissimus dorsi attach is being challenged if your posture is not good and you are now holding yourself up to avoid hitting those first two balls. The best thing you can do is to 1. Get on the stretching program listed on some of the previous threads. I list a series that attend to the whole body so you can challenge the arms and the core. 2. Strength train but use lighter weight and more strict, slow movements to create full ranges of motion. You're not trying to create bulk or necessarily size (even though you will see slight increases) so keep it below 8 pounds; try bicep curls, hammer curls for biceps and tricep kickbacks and nose crunchers for triceps, forward raises, side lateral raises, and rear deltoid raises for the deltoids. For you chest be sure you are doing a butterfly motion and some sort of rowing actions with your hands both close to the body and wide from the body. Any basic strength training book will have these exercises (I love to go to the library and get some of the old standbys) and all can be accomplished with minimal weight in the comfort of your own home. You may be surprised that a 5 pound dumbbell will really challenge your deltoids if you are keeping your form (which usually means keeping your body still). If you are truly looking at well rounded fitness these exercises are only a small part of the package but these will get you started. 3. Rest between workouts atleast one full day. 4. After you have been on the driving range (especially) or on the golf course, if you feel a little sore then you are right. You are using the muscles differently and they should adapt to the new stress conditions barring some gross structural problem. Use heat on the muscles after the range either with a topical rub, heating pad, hot shower or a massage. This treatment helps to bring blood into the muscle to begin to heal the trauma created in overuse conditions.
It is just the nature of golf that we are repeatedly creating an specific action that can cause trauma. The body is designed to recover given enough rest and respect to the natural mechanical capability of the joints. Since it's been almost two weeks since your post I hope you are enjoying some relief. Please try heat for the muscle (ice is for join pain) releif and minimize the use of pain killers like aleve and advil.
Let me know how things are going. I will check the posts every two days and see how you are coming along. Vickie