Etwas
The word »etwas« is the neuter form of the distinct indefinit-pronoun
etewer
which meant: »someone« or »something«. Germanists think, that etewer is a load-translation of the latin word
aliquid
(again meaning: »something«)
This word (etewer/etewas/etwas) was also used to name vague and undefined amounts of something, and so lso became the meaning of »a little bit of«:
Etwas Salz = ein wenig Salz
»Etewer« is built from two parts: »et(e)« plus »wer/was«. For »wer« and »was« see below.
The German prefix »et« (or »ete« in distinct words) can also be found in »etlich« (an undefined numeral) and in »etwa« (an adverb):
Gerd hat bereits etliche Wettkämpfe gewonnen.
In Österreich leben etwa 8,7 Millionen Menschen.
This »et-« always means that something has an undefined amount. It can me much but also little. »Et-« just says that you don't know the exact number.
Was
The word »was« is often used as synonym for »etwas«, like in your example, and in this case it is an indefinite pronoun like etwas. It is (together with its "twin" »wer«) a very old indogermanic pronoun. »Wer« and »was« and the English words »who« and »what« derive from the same protoindogermanic roots »*kʷo-« and »*kʷe-«.
But »was« can also appear in two other flavors:
- as interrogativ pronoun:
Was siehst du?
- as relative pronoun:
Das ist alles, was ich habe.
But those two forms can not be thought as short forms of »etwas«. This is only possible for the
- indefinite pronoun:
Ich weis nicht, ob an dem Fall wirklich was dran ist.
Ich weis nicht, ob an dem Fall wirklich etwas dran ist.