Inflation is the loss of purchasing power per unit, period. I know you are probably one of those "don't confuse me with the facts" people but 2 BTC bought a lot more two months ago, regardless of exchanging it for fiat. That is called inflation.
You can't measure inflation over a period as short as 2 months and with a single metric. What you experienced was volatility.
Inflation is a persistent and general rise in price of goods and services. You can not conclusively point to inflation for a change in exchange rate of BTC in a 2 month window. Compared to 12 months prior the purchasing power of BTC is much higher today. So are we experiencing deflation?