Well, first, I have to say that it is normal to have diplopia after the surgery. And you should know that diplopia named as double vision, is a condition in which, whenever you look at any object, you see its two images rather than one. So for your situation, I also need to tell you that you may be infected by some irritants. In common, after eye surgery, it is easy to get infection. And then, double vision can be possible. For the symptoms, pain around the eyes, such as in the temples or eyebrows can be possible. To treat it, you can wear an eye patch or special prism glasses to minimize the effect of double vision. Also, just find out the infection cause and have some medical cares. If the situation is serious, just go and see the eye doctor as soon as possible.
Diplopia is the so called double vision. You don't have the problem before the squint surgery, and it can be a temporary symptom after this surgery. It is a common side effect from squint surgery. There are six muscles which control the movement of eyeball. Squint surgery would adjust the balance of these muscles to align the two eyes. If the double vision tends to persist, then you need to consult your surgeon. As many part of the vision system need to cooperate together to get a good vision, the possible causes of diplopia include cornea problems, lens problems, muscles problems, nerve problems and brain problems. Since your double vision occurs after the squint surgery which adjusted your eye muscles, I assume that it is caused by muscles problems probably. As to diplopia caused by muscles problems, I am afraid you need a surgery to correct it. If it can't be reversed, then the doctor still have some way out for you. A kind of special prism glasses or a patching can help reduce the effect of diplopia.