Tire liners can help or you can STAY OUT OF THE THORNS....
You may have a pinched flat from changing your tube. Did you check where the hole or rip in the tube was in relation to how it was on the rim? Did you check the inside of the tire for another thorn or anything else before you changed the tube the second time?
You must be smarter than the trails and roads you travel to avoid constant flats, Know how to properly install a tube and use some kind of flat protection (Mr Tuffy is what I use) and they will add rotational weight to your tires but that probably wont matter to you anyway. these STOP thorns!