I had a similar experience when I was getting into pipe smoking and discovered that my mouth and throat are rather picky about what they do and don't tolerate and had to do a bit of a process of elimination to figure out what was bothering me. I bought samples of a couple dozen different blends at once when I started pipe smoking and was smoking different blends every day, but the mouth and throat irritation I was experiencing would often start late in the day or the following day and persist or worsen for several days afterwards so I never knew which blends or components were giving me trouble.
To solve that problem I waited until my mouth and throat were completely back to normal, then would smoke just one blend every day for a week and write down my experiences with it. If the blend was obviously giving me trouble after a few days though I'd shelve it and take the rest of the week off for my mouth and throat to recover before trying a different blend the following week.
What I learned from a couple years of trial and error is my throat is very intolerant of Burley and any blend containing Burley will give me a sore throat, unless it has been fire cured to turn it into Dark-Fired Kentucky or steam pressed to soften the rough edges then it's just fine. For instance, Cornell & Diehl's Burley blends absolutely destroy my throat and even OTC Burley blends like Prince Albert will beat it up pretty badly, but Gawith Hoggarth's steam pressed flakes containing Burley don't bother me at all. Additionally, any quantity of Perique is absolutely a no-go for me as well and will make my throat sore and cause the lymph nodes under my jaw to swell up something fierce. The only exception to that has been Peterson Nightcap, which weirdly doesn't bother me at all, but any of the over a dozen other blends containing Perique I've tried will give my throat fits.
Conversely, what does work just fine for me has been bright, orange, and red Virginias, dark-fired Virginias, Dark-Fired Kentucky, Black Cavendish, and Latakia. Basically, as long as I avoid Perique and any Burley that hasn't been dark-fired or steam pressed my mouth and throat feel just fine.
I would add though that any tobacco burning hot enough can cause irritation to the soft palate on the roof of your mouth, and bright Virginias especially due to the high acidity of the smoke they produce, so take your time and sip your pipe slowly to avoid mouth irritation. I find it helpful to keep the button on the end of the stem positioned towards the middle of my mouth, so the smoke exiting the stem isn't flowing out against the roof of my mouth or my tongue. If you can do that and keep the tobacco burning slow and cool that can go a long way towards preventing soreness of the tongue or roof of your mouth after smoking.