I am male 34 years and 2 months ago I noticed that my left testicle is harder and less soft than the other when I touch it. Also when I squeeze both with the same strength I feel gradual pain on the left one but not on the right testicle. In general when I stress it (by sitting, trousers e.t.c) I feel this light pain on my left testicle. The situation is not worsening but it's not how it was 2 months ago.The size additionally has not changed. Could you please give me an advice of what to do and if it's something serious?