Middle Primitive Elvish
kwam
root. *sick
gem
root. *sick
geng
root. *sick
There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
A root connected to sickness, first appearing as ᴱ√QAMA from the Qenya Lexicon of the 1910s with derivatives like ᴱQ. qáme “sickness, nausea”, ᴱQ. qama- “to be ill, vomit”, G. cwam “ill”, and G. côma “disease, illness” (QL/76; GL/26, 28). It reappeared in The Etymologies of the 1930s as ᴹ√KWAM with derivatives ᴹQ. qáme, N. paw and Ilk. côm “sickness” (Ety/KWAM). It does not appear again in Tolkien’s later writing, but there is nothing contradicting its validity either.