You can try this tool, PDF Creator Pro, which supports to combine multiple images into one PDF. You can add the images orderly, or adjust their position after adding them to the PDF creator.
you could use imagemagick tool- covert, to combine images. since the tool i available in command line, you can script with it. image magic. convert could combine your multiple images into one. to convert into pdf, convert can do that too. but if u have a mix of text and images to be put in pdf, i suggest latex would be a suitable option.
It's a very easy and quick thing you need Adobe Acrobat Professional and there is a option called combine files into single PDF just click on it add your jpg files and click on combin.. your PDF will be ready in a minute.