It is a little difficult to say what might have happened to you without a slightly more detailed description of where the needles were applied. It is possible that the insertion of needles has left a small bruise or bruises deep within the tissue. If these have consolidated then it will be rather like kneeling on a grain of rice or piece of grit. This can have a disproportionately large effect for the size of the irritant. However, for this to be the case the needles would have had to be inserted in an area where we would not normally expect a needle to be placed. As we said, without knowing more specifically where the needles were placed it is difficult to be sure.
What we cam be more certain about is the fact that acupuncture treatment very rarely causes permanent damage to body tissue, and even where there is bruising this usually resolves within a matter of days. If a needle has been inserted into an area where there is subsequent pressure from direct contact or from the flexing of muscles then this might cause some discomfort, but this will soon pass.
The other option which we have to bear in mind is that a small piece of needle has been broken off and lies within the tissue. This would be highly unusual, because most practitioners, certainly in the UK, use single-use disposable needles which are discarded after one insertion. The only reasons a needle can break are faulty manufacture or repeated re-use and sterilisation. This can make the steel brittle, and more likely to fracture. We haven't seen or heard of a case in the UK for well over twenty years, and even that was hotly disputed. If you are based elsewhere than the UK, though, this might be a relevant question to ask.
In any event, the best person to discuss this with is the practitioner who applied the needles. He or she will know exactly where they were placed, and this will give a much clearer indication of what might have happened.
Of course, we always have to bear in mind that a symptom may not be directly related to a treatment. With over 4 million treatments in the UK alone each year it is always possible that a problem, even in the same area, may not have been caused by the treatment. Our advice is always the same - if something persists for more than 48 hours it is worth getting a medical opinion rather than getting into discussions about what caused it. The medical assessment usually reveals what happened and the patient can then get the appropriate help as soon as possible.
We hope that the problem resolves of its own accord and that it has not put you off having further treatment.