“I have no visible caries, but my teeth can become extremely painful when I eat something hot or cold. Some spices, like chili also aggravates my teeth. This is only with my molars, but when I look at them I cannot see any problems, no chipping and no discoloration either. My tooth also becomes painful if it is cold outside and I go out from inside, or if my mouth dries out. But then it just goes back to normal. The tooth does not hurt if I touch it. Is there help? Do I just need to grin and bear it?”
When it comes to dentistry, grinning and bearing it is never a solution. If you feel pain, discomfort, heightened sensitivity, that is the sign of a problem, a potentially life threatening one. There could be any number of things wrong, what is sure is that although your nerve was not acting up until now, it is now experiencing some kind of problem that is making it react to outside stimuli. This can be because of improper amounts or types of tooth material around the nerve, it can be because of an infection of the gums that is constricting the nerve, or it can be because of some kind of damage to the nerve itself.
To give a proper analysis of what is wrong with the tooth in question, I would have to take a look at the area first. Without this, and based on your description of the problem, I think the problem you are experiencing is dentine hypersensitivity. This condition causes sensitivity of the tooth like you described, and can do so without swelling, caries, or any visible problem with the tooth. Basically, this condition arises when you have bits of your enamel missing. The enamel keeps the dentine in a layer of hard, calcified material, thus insulating the nerve totally and completely, and this is why you will not experience pain from regular things like biting and chewing. When this layer comes off, it may not be visible, although sometimes cracks can be seen on the tooth surface, and sometimes a greyer color can be detected, but not necessarily.
The teeth, when they start losing dentine will respond to pressure, changes in temperature, or even just the wind or exposure to air. The nerve will eventually become infected if you do not take care of this problem, and then it will hurt all the time. This may happen in a month, or even a year, or even five years, but sooner or later, your nerve will not be able to fight off the outside world. This is why it needs dentine and enamel to begin with.
I recommend seeing a dentist before something more serious and painful happens. This is necessary, and will probably only take a few minutes. Your dentist will apply composite filling material to your tooth, and thus insulate the dentine further. This way, your sensitivity will cease, and you will be able to get back to enjoying life and going outside without clenching up first.