Did you notice this recent post ⚠️ ↗ on Language Log?
'Sh' is one sound and it has its own phonetic symbol (I don't remember how I could produce that symbol here; it looks a little like a lowercase f, you know, but longer and without the small horizontal line).
The IPA symbol for the "voiceless palato-alveolar median laminal fricative" (Pullum/Ladusaw, Phonetic Symbol Guide, p. 173) is known as "Esh". It's ʃ, the Unicode Codepoint is U+0283 (and the corresponding HTML entity is ʃ, that's what you use to write it on GC).Surf safe;)
NFiH