javascript – Regex – match a pattern only if it is after or before certain pattern

I have giant string (markdown) that contains something like this:

## Header 1

{~1.0} Lorem ipsum dolor sit amet. Sed congue diam
turpis, {~2.0} vitae congue erat accumsan nec. {~3.0}

{~4.0} Lorem ipsum dolor sit amet. Sed congue diam turpis, {~5.0}
vitae congue erat accumsan nec. {~6.0}

{~7.0} Lorem ipsum dolor sit amet. Sed congue diam turpis, {~8.0}
vitae congue erat accumsan nec. {~9.0}

## Header 2

{~10.0} Lorem ipsum dolor sit amet. Sed congue diam turpis, {~11.0}
vitae congue erat accumsan nec. {~12.0}

{~113.0} Lorem ipsum dolor sit amet. Sed congue diam turpis, {~14.0}
vitae congue erat accumsan nec. {~15.0}

{~16.0} Lorem ipsum dolor sit amet. Sed congue diam turpis, {~17.0}
vitae congue erat accumsan nec. {~18.0}

## Header 3

{~19.0} Lorem ipsum dolor sit amet. Sed congue diam turpis, {~20.0}
vitae congue erat accumsan nec. {~21.0}

{~22.0} Lorem ipsum dolor sit amet. Sed congue diam turpis, {~23.0}
vitae congue erat accumsan nec. {~24.0}

{~25.0} Lorem ipsum dolor sit amet. Sed congue diam turpis, {~26.0}
vitae congue erat accumsan nec. {~27.0}

This is a marker {~x.x}

And I will call “section” to the combination of a header and one more more paragraphs.

I need to match the first and the last marker of every section.

Currently I’m using this regex /\s?{([^}]*(~\d*(?:\.\d+)?)[^}]*)}\s?/g in javascript that I got from the selected answer of this question to capture all the markers, but now I need to modify it to capture only the first and the last ones from every ‘section’.

The string comes from user input so I cannot know in advance how many paragraphs a ‘section’ will have neither the content of the headers, all that I know is that there will be at least one section (meaning one header followed by x amount of paragraphs).