Can't keep up with follow up tasks

I am generally very organized. Use various tools for different needs. But what's killing me is the constant influx of follow-up tasks after a call or email. If I stopped to write them all down, I'd never have time to work on doing them. But if I don't have them all written in one place, it's impossible to figure out how to prioritize them. So I end up with a million notes to myself, chasing what seems either most important or most urgent. I hate this feeling. Is there some workflow thing or tool that I'm missing here? The role is sort of a combo of sales and customer service. Not much prospecting; it's the same set of about 120 accounts across about 45 - 50 products. So if you're working with Bob on item 1, there is almost inevitably a slide into discussion of 2 - 5 unrelated items that generate entirely new to-do items. Also we don't really have sales tools - a CRM that is basically a glorified rolodex, one decent tool to help manage email sends, but nothing to help manage to-do lists or pipelines or anything. Any ideas??? I don't even know what kind of software I could ask for. Have never done sales before this job, so I don't have the standard experience to lean on.