Consumer prices in the United States rose again in April, and measures of underlying inflation stayed high, a sign that further declines in inflation are likely to be slow and bumpy. Prices increased 0.4% from March to April, up from a 0.1% rise from February to March. Compared with a year earlier, prices climbed 4.9%, down slightly from March’s year-over-year increase. The April data provided some evidence of cooling inflation, a sign that sent stock prices higher in morning trading. Grocery prices fell for a second straight month. And the cost of many services, including airline fares and hotel rooms, plunged.