My opinion is this taper is way way too fast for a long-time Paxil user. I would go a whole lot slower. I would also stop Paxil altogether and only when I was past any withdrawal would I start the Lexapro. So far you're doing pretty well, but this can be a tough slog for some people so I'd find out first if you're one of them. To avoid it as best you can, I'd take, as I say, as long as you need, not somebody's preordained schedule. There is no one schedule for anyone, and especially not from Paxil. Keep in mind that for whatever reason Paxil tends to hit those choline and serotonin receptors harder than other ssris (snris are also very tough to stop) so the Lexapro isn't going to be as strong in its affinity for them. I don't know why, but it just seems to be the case for many people. So take it slow, relax, and when you know you're cool then start the Lexapro, and take the above advice, start with 5mg and work up, it's again just safer that way. This is just my advice, because you might have the easiest time at this as anyone ever did. You just never know so why rush it?
I do not encourage you take anything outside of what is ordered at this point. This is possibly part of the anxiety. It will be Monday soon and you can give a simple call into your doctor's office. Let them know your symptoms and how bad they are, if the doctor feels it is of concern then you two can discuss changing the plan. Changing the plan on your own and taking any amount different than prescribed is dangerous and may cause other/worse symptoms. You could also suggest giving an extra week at 5mg Lexapro to give your body a little longer to adjust to this new chemical.
Headaches, temperature fluctuations, breathing fluctuations, minor aches, etc. can be common with titrating meds..
Patience and contact the doctor if you feel you there is need.