Complex sentence: Sufferers are often stigmatized, because both medical professionals and the general public tends to think that it is not "real", but specialists consider that pain from psychological source is no less actual or hurtful than pain from other sources.
Split into simpler sentences: Sufferers are often stigmatized, because both medical professionals and the general public tends to think that pain from psychological source is not "real". However, specialists consider that it is no less actual or hurtful than pain from other sources.