Veins are blue because they carry blood that lacks oxygen. Arteries carry blood that has oxygen, so the blood is red.
If you look at the palm side of your wrist, you'll see a bunch of purple vessels, which are the veins carrying blood that has delivered the oxygen to the hand and is on the way back to the heart to pick up fresh oxygen. This is the cycle that keeps us alive.
If you have them showing up suddenly in your arm and chest, it could mean a blood clot has blocked the flow, and now they are sticking out more than usual.
Please realize this: I am limited to the information that I glean from your posts, as I can't see, talk to, or touch you. I can only give you my approach to the evaluation of your symptoms if you were in my office. That puts me at a disadvantage compared to your doctor who actually sees your body right there in the office. This is just the nature of advising across the internet. A specific diagnosis under these conditions is VERY difficult.
1. Keep your arm elevated as much as possible.
2. Apply ice to the skin 15 minutes at a time.
3. If it persists for 24 hours, then you should contact your primary care physician as there may be a problem that needs to be evaluated.
4. Avoid heavy lifting over 20 lbs with that arm for the time being.
5. This is probably a transient episode that will resolve on it's own.
It often happens when you get flushing attacks, are anxious, or have fear. This increases vein flow and they become more visible.
They often tend to bulge when exercising, as I'm sure you're aware.
So, this is NOT a scary or dangerous condition unless it persists and you start to have other symptoms such as sweats, chest discomfort, or arm weakness.
If those symptoms develop, then off to the Emergency Room for a check for blood clots.
If you have ANY questions about what I wrote, please write back for clarification. I'm happy to continue working with you toward a resolution.