Hi mate. Sometimes when you train chest you can press your neck and head quite firmly into the bench. This can cause damage to the discs in your neck, resulting in the sypmtoms you're describing.
My advice is to see your Physio, have an assessment and treatment and see if it helps. If not, then they will advise you to see your doc for some scans. Try taking some anti-inflammatories as well to see if this helps. Ask your pharmacist or doc for advice here.
Hard to say what you've done without examining you, but I've also injured my neck with heavy chest when pressing awkwardly. I'm sure Take2 will have a comment about this also.
Let us know how you get on.
BD
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