Red bump on arm feels like a ball hurts only when I rub or push down noticed it today making my left shoulder kinda sore could it have ben poison spid

Doubtful spider bite. Spider bites are painful, form a small black ulcer from the venom the spider injects with a bite. Your lump does not sound like this. Many, Many things on the list of what this might be (lipoma, inclusion cyst, lymph node) to name a few. Only way to know what it is, evaluation. Can watch for next 1-2 weeks. If still there then eval, if worse eval. Also leave it alone to not irritate it. Dr R.