First, I want to tell you I give you kudos for nursing while being a full-time worker. And like several others, I would encourage you to make sure you are getting plenty of water and as much rest as possible (yeah, I know you are working and have a 5 month old -- but if you can, on weekends nap when your baby naps so you can be well rested.) Also, I would caution you to supplement with formula unless of course your baby is losing weight. Because as I'm sure you are aware...breastfeeding is based on a supply and demand principle, so you don't want to interfere with the demand part of the cycle.
Secondly, I want to address the spitting up. I have several suggestions:
I suggest stopping the Mother's milk tea. It probably is not affecting your child negatively, but it doesn't hurt to stop for a short time. See if that makes a difference.
You could eliminate any dairy products from your diet and see if that makes a difference, but it would be less likely that this is the problem since your baby is 5 months old (and never had the reflux previously).
And if neither of these work to improve the reflux, then you probably need to make an appointment with your baby's doctor. In the meantime, you can also raise the head of your baby's bed slightly by placing a blanket or towel roll under the mattress. Keep the baby positioned upright for at least 20 minutes after a feeding, and minimize bouncing immediately after feeding sessions.
Hope this helps...and by the way: prior to being a SAHM, I was a pediatric nurse practitioner -- my bottom line is that if the reflux is a new thing, don't sit on it too long, as it could be an indication of something else, that the pediatrician could find with exam.