I'm having hard time swallowing, can this be a sign of amyotrophic lateral sclerosis?

Unlikely. While dysphagia (difficulty swallowing) can be a herald of als, this is a very, very rare disease, and dysphagia is a common symptom. Depending on your age, what you have trouble swallowing, and other medical issues you have, there are a host of potential causes for dysphagia. See your physician and discuss it with him/her, include what is hard to swallow, when, when it started. Good luck.
Swallowing problems. It wpuld be unusual as isolated symptom. If persosts you should consult and have a swallowing study.
Let's analyze. Swallowing issues occur late in the course of ALS, unless a very aggressive bulbar form. The disease occurs later in life, not usually in 20's. Absence of muscle weakness, fasciculations, atrophy, tongue weakness, would make ALS unlikely diagnosis. Your swallowing problem could be a structural esophageal issue, a complication of sinus discharge or GERD, and even muscle or myasthenia issue.