It does happen, and believe me it does go away 100% over time. Try to ignore it, or, like I did, reduce your dosage to 0.5mg EOD (every other day) and increase to 0.5mg daily, then 1mg daily whenever you feel comfortable upping your dosage, usually as side effects like testicular pain begin to wane. Trust me. Just try to ignore it. You are not causing yourself any damage. The pain is caused by your hormone changes, but once your hormones stabilize after a few weeks of use, (you may have testicular pain for up to 2 months, but it will be heavily reduced) the pain will go away. It is distracting, I know, just try to ignore it. It is a normal part of the process that almost everyone seems to go through. You are changing your body's internal chemistry very quickly, and the body is merely reacting to these changes. Once the DHT is stabilized in your system, the testicles will stop freaking out.
The important thing is to remain consistent. These days are paramount. Do not forget a day. Forgetting a day is OK from time to time when you're a few months in, but you do not want your body to be up and down off the bat. Reduce your dosage if necessary, but stay relatively consistent for at least the first month. Side effects you may experience are usually due to hormonal shock, and once the body adjusts to the changes, it will stop panicing and resume life as usual. Your body simply does not understand what is going on, and eventually it will accept the medication. Keep on taking the drug for at least 3 months before deciding it is not for you. These symptoms are NOT permanent and do go away 100% if you decide this is not for you, but side effects do go away 90-100% after about 4 months on the drug. Some people's bodies are just very sensitive to hormone imbalances, like mine. Keep with it and you will be a hot hairy mother ****er well into your 50s.
Your side effects may get worse if you decide to stop, initially, because your body is again experiencing a hormonal imbalance in the opposite direction. But you will return to normal in about a week, but this time does vary from person to person. Keep in mind that not everyone's body is the same, and we all experience side effects differently depending on our genetics, diet, amount of exercise, and other factors. Just stick with it and have faith.
But MOST OF ALL, do not listen to all of the fear mongering about propecia. Some people have bad experiences with the drug, but those are a vocal minority. Fear and anxiety will only cause worse side effects. Keep your mind off of it, keep working, do not even begin to think that any of this is permanent, and frankly avoid these forums unless you require serious medical help.