There is some suggestion that excessive periodic movements like the one you have explained and you think it is hiccups may be harmful but has not been proven. It is impossible to say what the cause is in your case or indeed any individual case. Normally in low risk pregnancy there is no point in being too paranoid and if there is no complication like blood pressure and diabetes, etc you should not be too worried. However if you are still worried, you can go and get a Biophysical Profile / Non stress test but none of these tests will prove that your baby is in trouble or in fact reassure you beyond a point. The best is to get in touch with your treating physician and let him/her decide what to do. Each doctor / hospital has a protocol / policy.
Here I can tell you that too many ultrasounds and tests lead to too many caesarians and not essentially save otherwise endangered babies. But the way things are, you would probably be told to get these tests. Even if the baby has a cord around the neck, almost a third of all babies do, it is dangerous only if these are more than 2 or 3 times round the neck or there are other problems like a very short cord. All these need careful evaluation and the decision of doing a caesarean should be evaluated against the possibility of delivering a premature baby. To answer your question directly you do not need to get too worried as this answer gives a concept and not a proven scientific fact. You can see your doctor and get a detailed examination done including an Ultrasound examination.